I pulled the message below from another forum. Hope it helps.
I just finished a laminate kitchen cabinet. After cleaning with TSP and sanding, I primed then painted, and finished with a clear varathane. I did this several years ago on a laminate dresser for the kids room and the paint is still sticking. I also read that a good crackling agent is the kids glue that comes in the bottle with the rubber tip. Much cheaper. I haven't tried that yet because I'm having trouble finding that old style glue amid all the new gels.