Have you tried the standard RCA TV discrete on and off in the discrete files section?
[Link: remotecentral.com]If it uses the standard RCA command set it uses the discrete on commands for RCA brand DVD's, DSS receivers, and VCR's for those discrete input selects. The theory is that you turn on the gear and set the input with one command if you have all RCA equipment. Philips does much of the same thing.
There are discrete commands posted for each of those and at the link above. You can give them a try. If those work I can probably come up with the others.
If those don't work, learn and post the pronto hex for the power toggle and I may be able to recognize the command set that belongs to some other Plasma manufacturer.