Diabolical !
I want one , but for $20 US , it has already been invented, how much is your time worth? I think a PIC would probably do it. Go over to Bruce's website, he has lots of IR example code there :
http://www.rentron.com/
You will need to send out ALL the various on/off commands for each and every TV protocol, plenty of brain damage collecting all that,, but heck, do it for kicks.