I've had mixed results.
You can try color remover first to help. Simple colors are easier (not mixes of powders). White bodies do brighter colors. I've successfully turned blue to purple and black. Also whiteish to yellow (my baits have been halfway there which is helpful).
Use Rit or equivalent dyes. Walmart brand dyes are only good if you want a mottled color. I use both salt and vinegar in hopes that it takes. Seal after completely dry so that you don't transfer color as you handle it.
I'm nowhere near perfect at it and have still had to FBR more than I would like.