helping a buddy assemble a custom tele. he's got himself a very nice neck from, i believe, musikraft, and has found it has sharp edges on quite a few of the frets
( i mean where they stick out too far over the sides of the fingerboard and haven't been sanded/filed down properly).

what sort of files and sandpaper would one want to use, and what methods to avoid damaging the finish?

would have searched the forums here, but didn't know what search terms to use.

should i send this one out to a specialist? is it worth trying if you haven't done it before?

A dressing file is the tool that you need.

As was recommended to me when I asked a similar question - ideal tool for the job - then all you need is some tape to mask off the finish, and lots of patience!!
go to any tool store and pick up a basic set of steel files, NOT DIAMOND. there will be a 3-sided file in it, shaped like a triangle. you need a flat surface and some 150 grit sandpaper or so and you want to smooth out the edges of the file. then put that edge down on the fretboard and dress the ends of the frets with it.