I am an AV installer and systems integrator...this is hands down the BEST windows based app for browsing and playing your mp3 library! But to use this in residential applications we need some way to control it externally. The best option would be RS-232 codes that can be sent to the computers COM port that eJukebox will recognize and respond to. The next best option would be full keyboard control (i.e. for every action in eJukebox there is an equivalent keystroke). Maybe this is being done, I dunno, any thoughts?

I've got no idea about rs-232 codes. However you can find ej keystrokes at http://www.audiosoft.net/forums/viewthread.php?tid=4 It might be a little outdated though.. But at least it includes keystrokes to the most basal functions within the software... Remember to hold down ctrl while using the strokes in the albumlist. This is to override the "jump to letter" function.

eJukebox already supports a large array of keyboard commands and we will be adding more in the future.

When you install eJukebox - it places a list of the Current keyboard shortcuts at: Crogram FileseJukeboxKeyboard Shortcuts.txt

Personally i already use the serial port to control eJukebox with a infrared remote control. I have a IR diode connected to a COM port of my PC.
You can find on the web many specialised software like "Girder" http://www.girder.nl/ - it's a freeware! - which can convert the serial codes and simulate keyboard keys or even mouse moving, and send them to any Windows application you want.
That works great to control eJukebox!