I hope So!!

I have a pickguard that is two months old and it looks fine.

I have read where one of the sellers of the guitar dyes recommended RIT black mixed with his red for a black cherry effect which indicates that is should be colorfast.

The lacquer thinner makes them soak right into the wood, so I would say yes. I suspect they may be the same material as the powdered wood dyes.

My new guitar isn't a USA Custom, but go to Bill Lawrence WildeGate to see a picture.