why would you want to do such a thing? If you leave the routers routing, then no you can't do it, well you can, traffic just won't be able to go from hq to remote. You could probably come up with some complicated solution using bvi's. something along the lines creating a bridge group, then assigning the bridge group to the serial interface and the fa interface, then creating a bvi and giving that an ip address. kind of a cludge and not sure that it would work.
