It involved cutting up the inside of the frame. There are two "pockets" (1 on each side, inside the frame there) that have to be cut out for a tm24 to fit. You can't tell unless the carb is out and you're looking inside. The wiring normally goes through those pockets, but I re-did the wiring on the bike, hardwired it, ran new wires, etc. so they don't run through the pockets (since they don't exist anymore). I had to remove the subframe, all the wiring, cables. etc to cut the pockets out, it was a lot of work to put a tm24 in there.
I'm sure you know about those pockets that i'm referring to since you own a revo or two.
Thanks for your question!