The Blackwidow uses Kailh switches (sometimes referred to as Kailua) which are functionally almost identical to Cherry MX switches. There are oodles of guides on changing springs/stems on Cherry MX switches, and the forum is rife with useful information for disassembly of cherry MX switches too (check the
post on switch lubrication, there's a video in the first post)
edit: I'm assuming you mean changing out the switches and stems to a different variation of cherry MX, and not, say, switching to ALPS switches or something.