2 NIC’s on a TS

Hello..
Im working on a TS with 2 nic’s. One Nic is going to a DSL line in the building and the other nic is going to a T1 line. What i need to do is connect them to the TS without having to take them off of the T1. I need them to connect to the TS using RDP while they are on the T1 line. Can Anyone please help.. I need it ASAP.. Thanks