Answering my own question, I added
activate_this = 'c:\\Program Files\\.....\\installer\\bloodhound\\Scripts\\activate_this.py'
execfile(activate_this, dict(__file__=activate_this))to trac.wsgi and that seemed to do the trick. I hope that's the correct way to do this. If so, this might be a valuable addition to the Install documentation.
-R.C.