Thats actualy very simple.
you can use a T1 crossover cables to simulate the WAN.And a router in Frame-relay switch mode.
All wic modules need to be configured for the same bandwidth. If it is a 56k/64k module then the bandwidth is already set. For the WIC T1 dus/csu module, set the linecode, framing, and timeslots on each of the modules. One set the clock to internal the other to line.
For the T1 setup create a T1 crossover. first end connect pins 1,2 to pins 4,5 at the other end, then first end connect pins 4,5 to pings 1,2 at the other end. You will have to have the router a frame-relay switch mode to addvertize the dlci's
So your topo will look like this
cpe router----frame-switch-------cpe router
For the 56k/64k its the same except you will not configure the timeslots on the modules, and I believe the pins are 1,2 and 7,8
As you can see you will need an extra router with 2 modules to provide the frame relay dlci's for the circuits.
In the frame switch you will map a dlci you specify on one interface to a dlci you specify on the other interface. this will bring up the frame-relay protocol and advertize the dlci's to the cpe equipment.
Gene