A good starting point would be a search for this regiment and/or Col Morgan and McRae's Brigade in the Official Records
http://ebooks.library.cornell.edu/m/moawar/waro.html

The Peter Wellington Alexander Papers provides an enormous amount of material on the regiments in Arkansas during the second half of 1862 more or less.
http://www.ozarkscivilwar.org/archives/4746

You can perform a search on this message board for Arkansas and find many relative posts including the following one by Bryan Howerton:

Posted By:

Bryan Howerton Date: Wednesday, 15 September 2004, at 9:41 p.m.

TWENTY-SIXTH ARKANSAS INFANTRY. Muster roll of officers present, September 30th, 1863:
NAMES. RANK. DATE OF APPOINTMENT.
Field and Staff. A. S. Morgan, Colonel, July 23d, 1862. B. A. Landon, Surgeon, July 19th, 1862. G. M. Wright, Adjutant, March 18th, 1863.
Co. A. William Simon, Captain [date of rank not stated] S. O. Feeney, Second Junior Lieutenant, August 7th, 1863.
Co. B. Sam Gibson, Captain, May 3d, 1862. James T. Caldwell, First Lieutenant, May 3d, 1862. Joseph S. Morgan, Second Senior Lieutenant, February 1st, 1863. B. R. Ragland, Second Junior Lieutenant, September 7th, 1863.
Co. C. William S. Otey, Captain, July 18th, 1862. J. H. B. Pross, Second Senior Lieutenant, May 12th, 1862.
Co. D. A. H. Holliday, Captain, May 12th, 1862. J. H. Prewitt, Second Senior Lieutenant, August 15th, 1862.
Co. E. James R. Stanley, Captain, May 12th, 1862. G. M. Reed, First Lieutenant, November 12th, 1862. J. W. McGaughey, Second Senior Lieutenant, November 12th, 1862. John E. Wylie, Second Junior Lieutenant, April 17th, 1863.
Co. F. Jesse Bland, First Lieutenant, June 16th, 1862.
Co. G. J. S. Brooks, Captain, July 18th, 1862. W. D. Jones, Second Senior Lieutenant, May 22d, 1862. W. H. Lemay, Second Junior Lieutenant, May 19th, 1863.
Co. H. J. W. May, Captain, June 13th, 1862. T. A. Cade, First Lieutenant, June 13th, 1862. R. F. Lassiter, Second Senior Lieutenant, June 13th, 1862. A. N. Martin, Second Junior Lieutenant, June 13th, 1862.
Co. I. J. R. Maxwell, Captain, June 16th, 1862. B. F. Quartermouse, First Lieutenant, June 16th, 1862. W. R. Marshal, Second Senior Lieutenant, June 16th, 1862.
Co. K. W. A. Bull, Captain, August 15th, 1862. Henry H. Hill, First Lieutenant, September 6th, 1862. J. L. Congo, Second Senior Lieutenant, September 6th, 1862.

Here's some more stuff I found while reorganizing my files. I can't remember if I've already posted these muster certificates for the various companies of the 26th Arkansas, so if this is a repeat, just put it down to a "senior moment".

COMPANY MUSTER-IN ROLL.
Muster Roll of Captain F. P. Yell’s Company in the _____ Regiment of Arkansas Volunteers, commanded by Col. __________, called into the service of the Confederate States in the Provisional Army, under the Provisions of the Act of Congress passed February ___, 1861, by __________ from the 3rd day of May, 1862, (date of this Muster) for the term of 3 years of during the War, unless sooner discharged.
Certificate of Mustering Officer.
I CERTIFY, ON HONOR, That I have carefully examined the men whose names are born on this Roll, and have accepted them into the service of the Confederate States for the term of 3 years or during the War, from this 3rd day of May, 1862.
A. G. GREENWOOD, Mustering Officer.
Date: May 3, 1862. Station: Monticello, Ark.

Muster Roll of Captain Sam Gibson’s Company in the _____ Regiment of Arkansas February ___, 1861, by __________ from the 3rd day of May, 1862, (date of this Muster) for the term of 3 years of during the War, unless sooner discharged.
term of 3 years or during the War, from this 3rd day of May, 1862.
A. G. GREENWOOD, Mustering Officer.
Date: 3rd day of May, 1862. Station: Monticello, Ark.

Muster Roll of Captain Tom McSwine’s Company in the _____ Regiment of Arkansas Volunteers, commanded by Col. A. G. Greenwood, called into the service of the Confederate States in the Provisional Army, under the Provisions of the Act of Congress passed February ___, 1861, by __________ from the 12th day of May, 1862, (date of this term of 3 years or during the War, from this 12th day of May, 1862.
A. G. GREENWOOD, Mustering Officer.
Date: May 12, 1862. Station: Pine Bluff, Ark.

Muster Roll of Captain A. H. Halliday’s Company in the _____ Regiment of Arkansas Volunteers, commanded by Col. A. G. Greenwood, called into the service of the passed February ___, 1861, by __________ from the 12th day of May, 1862, (date of this Muster) for the term of 3 years of during the War, unless sooner discharged.
term of 3 years or during the War, from this 12th day of May, 1862.
A. G. GREENWOOD, Mustering Officer.
Date: May 12, 1862. Station: Centreville, Bradley Co., Ark.

Muster Roll of Captain James P. Stanley’s Company “E” in the _____ Regiment of Arkansas Volunteers, commanded by Col. __________, passed February ___, 1861, by __________ from the 12th day of May, 1862, (date of this Muster) for the term of 3 years of during the War, unless sooner discharged.
term of 3 years or during the War, from this 12th day of May, 1862.
A. G. GREENWOOD, Mustering Officer.

Date: May 12, 1862. Station: Selma, Drew Co., Ark.
.
Muster Roll of Captain Angus F. McNeill’s Company in the _____ Regiment of Volunteers, commanded by Col. __________, called into the service of the Confederate February ___, 1861, by Maj. Genl T. C. Hindman from the 24th day of June, 1862, (date of this Muster) for the term of three years or the War, unless sooner discharged.
term of three years or the War, from this 24th day of June, 1862.
GEO. D. ALEXANDER, Capt. & Mustering Officer.
Date: June 24, 1862. Station: Little Rock, Ark.

Muster Roll of Captain J. W. May’s Company “H” of Lt. Col. Morgan’s Battalion (Nelson’s Brigade) of Arkansas Volunteers, commanded by Lt. Col. A. S. Morgan, called , by Maj. Genl Hindman from the 13th day of June, 1862, (date of this Muster) for the term of three years, unless sooner discharged.
term of three years, from this 13th day of June, 1862.
T. A. CUDE, Mustering Officer.
Date: July 1, 1862. Station: Fort Hindman.

Muster Roll of Captain John R. Maxwell’s Company “I” of Lt. Col. Morgan’s Battalion of Nelson’s Brigade of Arkansas Infantry, Army of the Confederate States of America, commanded by Lt. Col. A. S. Morgan, called into ____ from the 16th day of July, A.D. 1862, (date of this Muster) for the term of 3 years or the war, unless sooner discharged.
term of 3 years or the war, from this 16th day of July 1862.
Mustering Officer.
Date: July 16, 1862. Station: Camp Texas near Little Rock, Ark.

26th Arkansas--Record of Events
Posted By: Bryan Howerton Date: Tuesday, 11 February 2003, at 9:56 p.m.

COMPANY A.
…
30 Apr 1863—Little Rock. Since the organization of the Co. no books have been furnished and on account of the scarcity of stationery it has often been impossible to keep full record of all orders, details &c. Even now we have no Company Books and it is not possible to obtain them.
30 Jun 1863—Camp near Ft. Smith. Left Camp near Little Rock May 9th and arrived at Camp Anderson same day. Distance about 5 miles. Left Camp Anderson May 20th, 1863 and arrived at Camp near Fort Smith June 1st, 1863. Distance One Hundred & Seventy Five miles.
29 Feb 1864—Camp Sumter. Churchill’s Brg’d Jan. 30th/64 changed station from Camp Bragg to Camp Sumter, Ark., distance of 40 miles.

The Asa Morgan [first Colonel of the 26th] letters at the Butler Center are now available on line.
http://cdm15728.contentdm.oclc.org/cdm/search/collection/findingaids/searchterm/bc.mss.06.08/order/title

If you care to post your email, I will be happy to send you the notes I have accumulated on this regiment.