[Twisted-Python] access an XMLRPC service through an HTTP proxy

Hi, I'm using twisted.web.xmlrpc.Proxy to connect to an XMLRPC service. Unfortunately there are situations in which I have to go through an HTTP proxy, yet there doesn't seem to be an option for this (and looking at the code, the connection to the remote server is quite "harwired"). Is there a simple way to do this ? (write a new protocol factory perhaps ?) Also, is there a way to discover the OS's HTTP proxy settings ? (especially under Windows) Thanks Antoine.