Stephen, there are X-10 codes in the built-in TC1000 database. Try adding a device of type, "Home Controller." X10 is at the bottom of the list, and there is a single code set. It works great with my IR to X10 transceiver. The reason you may not be able to learn the codes from your X10 remote is that most of those remotes transmit X10 codes over radio--the IR LED is used only for A/V equipment.

Best of luck,
drew