Britton's books do not contain the rosters for the Union Indian Brigade (i.e., the three Indian Home Guard regiments).
The url for the Civil War Soldiers & Sailors website has changed to http://www.civilwar.nps.gov/cwss/index.html
Click on "Regiments" and then select:
Union or Confederate? = Union
State = Kansas
Unit No: = 2 (i.e., 2nd regiment)
Function = infantry (the IHG were "mounted infantry" when they had horses)
Unfortunately, you can only list 20 names at a time and their are over 2,600 men who enrolled over the course of the war (and there are duplicates) so you just have to go page by page. You can also search by name but only exact spellings, so you have to search for every possible spelling variation of a name and cross your fingers.