filling screw holes?

the po of my '79 seemed to like gadgets like cup holders, pvc rod holders, etc. i do not. that leaves me with about 20 screw holes in my boat, a few filled by po haphazardly (i.e. protruding shamelessly) with some hard white crap. i shaved down the hard white crap or just chiseled it out where need be to provide a recess for the real repair. question is, i don't know what to use for the fill. do you just epoxy and wet sand, then gelcoat and wet sand, compound, and wax? i don't understand the process as far as what the gelcoat actually consists of or does, and how it blends with the rest of the gelcoat. i'm pretty picky, and don't want to fly blind, so if anybody has a good screw hole filling method (insert guffaw here), i'd like to hear it. yes, i read the other gelcoat posts, but couldn't really garner a concrete process from start to finish. thanks.