We were previously using bugzilla's MySQL user table as our authentication database for other related websites.
Since we switched to FogBugz, we needed something similar, so I hacked up https://github.com/jaysoffian/mod_authn_fogbugz from mod_authn_dbd. It is dependent upon the current FogBugz sPasswordVersion (600) which uses an 8 character salt in combination with an md5 hash.
Hope this helps someone.