I have a warwick 5 with those brass frets,

I figured perhaps Noxon
and some of that blue painter's tape.
...to cover the fingerboard wood,
but I had to ask.

Go the the music store and grab a brass polishing cloth for saxamaphones. They work great

And don't use painters tape, make yourself one of these out of some tin or plastic:
http://www.stewmac.com/catalog/images_1lg/3741_1lg.jpg

thanks