Not sure if i understood correctly but if htpc is windows based you might try this :
http://www.internettablettalk.com/fo...ead.php?t=7226

You could ignore the x10 stuff and use the webserver to kick off macros/programs/batch files/ or possibly AppControl to control pc via web control pad. You'd basically have to configure the htpc's ir programs to work with dispatcher.

Its not a program specifically designed for your purpose but its a program semi-designed for alot of purposes... a kit you could try.