Rules for this are on the way. Vampires have a bunch of options:
6. Conversion - this is just an alternate version of Poison that ends in turning into a copy of the monster rather than death. For werewolves, zombies, vampires, Dimmies, etc. (Same as BW2001; planned for the Species section of Ch. 10.)
7. Thralls - sacrifice a follower (usually a lady follower) for an immediate-use Benny. For vampires, secret agents, lichs, priests, cult leaders, rock stars. (Ch. 11)
8. "Vampire" Heroic Feats - obviously
9. Revival - roll every turn to come back to life, unless properly staked (Ch. 10)
10. SuperNatural Powers - (Ch. 10)
11. Transformation - Vampires are always transforming into bats or wolves or clouds or something, but I have no plans for rules on this specifically. Maybe it can be covered by Vampire Feats.
BW2001 had a full set of rules for monsters and the like, you can raid chapter nine for ideas: http://www.brikwars.com/rules/2001/2001-bookthree.txt