I thought channel down was to cancel a macro being programmed.

In any case, I have found that the second screen in the AUX function has a few of the X-10 commands preprogrammed. For example, K2 corresponds to 'On', K8 is 'Off', K4 is 'Dim', K6 is 'Bright'. (I'm doing this from memory so I might be off on the exact button names.) Give it a try.