Comcast remote to control ATV problem

I've set up my Comcast remote to control the ATV using the AUX control. It works fine, but there are some buttons on the remote that seem to be permanently mapped to the cable box regardless of which input is selected. Most importantly, the OK/Select button in the middle of the 4-way controls will not work when in AUX mode. Does anyone know if there is a way around this limitation? (I've mapped "enter" and "back" to the "menu" and "info" buttons respectively, which isn't a bad compromise).