Passing VPN Through a Cisco Router

I have a Cisco 2514 router that connects my organization to the internet via a T1 to the internet.

I am two hops away from this router at a remote location. I am researching placing a VPN behind the router behind the second router due to the fact I am at a remote location. The VPN server will be in the DMZ.

Is there a way to pass either port 1723 (PPTP)or port 1701 (L2TP)through the router that performs NAT? If so, what syntax should I enter in the router(s)?

My intentions are to setup a WIN2k RRAS server with one NIC, if possible. Any insight would be appreciated.