The CM11/12 does support extended codes but the interface and protocol it uses is totally different than the XM10.
Ahh yes. Was misled by the similarity of external appearance and specs.

The CM11/12 has actually got some intelligence inside
Not sure that's always a good thing
I'll send you the CM11 protocol and the X10 extended commands bits.
Got it! Thanks! Much appreciated! Now off to do some serial port twiddling...