It uses a driver to decode the binary stream, good luck trying to do that yourself.
Theres really no need to write some other application anyway. The HD RadioPC app is completely customizable as it uses image files that you can modify. This is typically known as "skinable" software. You can also specify no skin and just embed the LCD portion into your own software or skin. You can issue commands using "sendwindow" or even keyboard keystrokes (ie. sendkey). You can also attach to its API to receive real time status updates and completely hide the HD Radio PC app from view. IOW, it exposes a driver with a complete API.
I just use an AC/DC power adapter from an old netgear router that stopped working long ago. Just about any 12v AC/DC adapter will work that is rated at 500 ma or more, you can pick one up for less than $10..