well this is what brought me to believe it would work with ultimate doom. this is a direct quote from the DOOM 64 TC Guide;
"The older version of Doom64TC worked with Ultimate Doom also, and this is probably still true. In this case, it will be the "doom.wad" you will need to copy and paste into Absolution's Bin folder."
just as clarification go to this link:
http://numerometria.com/d64tc.htm