I couldn't find anywhere else that had this and I don't remember how I discovered how to use it, but here it is if you need it. I'd edit it into the gtamodding.com wiki but I can't figure out how to edit pages there (do you have to be logged in? because it says that isn't required). Anyways, here's how it works. I've tested it, and it works.
SET_CHAR_ANIM_SPEED(ped p, str animation set, str animation name, float speed)
I have this implemented in one of my scripthook.net scripts like this
GTA.Native.Function.Call("SET_CHAR_ANIM_SPEED", PlayerChar, new GTA.Native.Parameter(str1), new GTA.Native.Parameter(str2), new GTA.Native.Parameter(2.0f));
If anyone would tell me how to edit pages on gtamodding.com it would be greatly appreciated.