Say I have a PPTP server running on physical subnet P on its eth0, serving virtual subnet V. I want to give a client connected into V access to a host in P which doesn't do PPTP. So, ideally, I'd be able to reroute traffic going to a V.X to a P.Y.

IP masquerading is cool but I'd like to do this without setting the PPTP server as the default gateway on the PPTP clients. Is there another way?