I just went through a similar exercise. I wanted to control streaming
video from the internet.
I use a program called IRCommand2http://www.wdpsoftware.com/
It was the easiest program I could find to set up.
It learns all your remotes. When you done teaching it your
remotes you are left with a keypad on the screen. Press a button
and it sends the IR command out the RS232 or USB port.
You need hardware which is not expensive.
This sounds like what you need. A person by the name of
Joe Mattioni from support was very helpful with my early questions