I don't think there should be any bother to try making CC99 plus compatible. It's essentially a butchered version of TSF with some HH98 levels. Less gamemodes, and for some reason the custom splitscreen "treasure" levels aren't even treasure at all and are actually supposed to be played in coop/sp. (wow whoever had tested CC99 before releasing, sucks at testing and should've been fired, though I could say pretty similar about those who tested TSF before release). Although if CC99 had all the features of TSF and some real new stuff with many bugfixes, I would consider it.

Short version: CC99 sucks. =/