Hmmm....
It allows for custom spritesheets, BUT...
it expects each frame to be 64x64 or 192x192.
This means that you can only arrange each frame wherever you need it to be in the spritesheet (since the frame size is fized, this is kinda of semi-custamizable. That could be done, but it would no longer be a LPC Character Generator)
You can place several animations in the same spritesheet, and that's the closest thing you get regarding categories.
Regarding color, if you are trying to have, for instance, several walking animations with different hues in the same spritesheet,that's not supported.
If you need a character to colorize in game, maybe using the grayscale palette option will work for you.
Regarding the size you the spritesheets, I don't know yet. I've been trying to reduce it has much as I can, because I have a potatoe PC, but your question got me really curious. I guess I'll try to create a spritesheet that large, with many repeated frames and a very fast animation speed, to see how it goes (I don't hold much hope though).