Hey Jon, the bass is looking great! I recently fretted my bubinga fivestring. When I built it as a lined fretless I coated the board with poly to avoid the bloodwood from browning much like you want to do with your paduak. I have to warn you it makes for a very bright sounding bass, which I like, others dont. Hell, I had to cut the slots while coated and it was still pretty straight foward and easy, so I dont think it would be to hard to clean the poly out of the slots if you spray it before fretting. You just have to be carefull. As a matter of fact thats the only way I would do it, because if you got a run or any orangepeel you'd have to sand it out and it'd be kinda hard with the frets in the way. You'll want to bevel the slots across the top to avoid chipping and tearout not only for installing but also for if you goof up and have to remove one. When dressing the frets I put multiple layers of masking tape between each one to cover the finish so I could work the frets with files and the crowning tool. Whenever I was ready to polish the frets I just buffed them and the board at once, it turned out very nice. Its a little more work but well worth the effort and I really think you'll like the results. Also I would suggest a hard 2part poly like what's used for automotive work, I used House of Kolor for mine and played it over a year fretless before I decided to fret it and It still looks as good as when I first did it. NEways heres a pic to show you what I did, of course this thing gets played like crazy so there are plenty of fingerprints all over it If you have any questions please feel free to ask.
Before Fretted!
http://img.photobucket.com/albums/v626/sco...bassbuffed2.jpg