You could program an IR sequence into the Source buttons. The first command (actually, the first two) would be the ZPR68 code, and after that add a unique code for each source, and each keypad. That way, the Ocelot could recognize the same button being pressed multiple times, on the same keypad.

Another, better, solution would be to buy a used Crestron controller on Ebay -- like one of these:
[Link: cgi.ebay.com]
[Link: cgi.ebay.com]
[Link: cgi.ebay.com]
[Link: cgi.ebay.com]

The Crestron could communicate with the ZPR via RS-232 and constantly monitor it's status. Then, it would be trivial for the Crestron to turn on/off equipment as desired. Of course you could do lot's of other cool stuff, too...