This module does not use user credentials to authenticate when using trac's xmlrpc interface.
I've added a few lines to accomplish that. You just have to certify that trac users have the same username/password that dP users and that passwords are stored and/or compared in the same format.
For me it works nicely cause I use dP as my user's database and trac authenticates against it using mod_auth_mysql.
class for authenticated access to trac's xmlrpc