The French site (English translation here)
did an upgrade to C2D 2.33 a few months ago -- and have excellent pictures:
They discuss chips and the Core Solo upgrade here:
Depending on your goals, it might also make sense to sell your old Mini and buy a new C2D Mini -- which would have a new 1-year warranty and be able to address 3 Gigs of RAM.
(I can't recall anyone addressing 3 Gig of RAM after upgrading a CD mini to C2D; there must be some difference in the support chips on the logic board.)