Hi,
You could also try vinyl sanding sealer: http://www.skguitar.com/SKGS/sk/winding2.htm
This description says it isn't suitable for metal covered pickups,
but I've done it to 3 metal covered pickup sets without a problem:
two LS-60s (Diodati's made by Tokai) with Gotoh's in them and
an Epi Wildkat with metal covered P90s.
I highly recommend this procedure because it's so simple and
has great results. The above described pickups would squeal
very easily and non-musically with even a modest amount of
distortion (though I think it was the compressor that was exacerbating
the problem). After the sealing process, the pickups never squealed
even at high distortion settings and the feedback was musical, i.e., related
to the notes that were vibrating in the chords I was playing. Thus,
the feedback was useful!
I now enjoy the guitars a lot more it saved me from having to replace
the pickups.
-- Bill