Bridging 2 lan segments over large routed IP network

I have a large IP network that I'd like to bridge two segments over for a temporary project. It's dead easy to bridge over a serial link, but I've never had to bridge over a routed IP network before.

Any suggestions? I did notice a post where someone had suggested DLSW+ but it looks like it's used for SNA. Can it encapsulate IP as well?

Or L2TP, but the configuration examples I've seen seem to be for a dial in user to dial into the LAC which connects to the LNS.

All I want to do is bridge two network segments together. This ought to be easy yes? I've got two loaded 2801 series routers to do this with...

Example configs would be MUCH appreciated... (or pointers to them)

Thanks in advance...