It shouldn't be that hard. Drow don't appear in significant numbers until very late in Book I. Book II might require more conversion work, as they appear early and hang around as a constant presence. Book III might present some unique problems in regards to the Threnody, a band of renegade Drow.
Anyhow, the baddies in th DW series need to be:
a) Organized. These are Lawful Evil villains for a reason
b) Subterranean.
c) Ancient. There has to be some bad historical blood between the villains and the Elves. Several plots depend on memories of ancient wrongs.
