Depends on the commands you want to output, but definitely do-able if you're willing to do a little kernel hacking.

By default, I'm not sure if any of the things it outputs on its serial port would be useful to you or would even be considered "commands". But the kernel is fully open-source and has already been heavily modified (mostly by Mark Lord, who made the Hijack kernel). There are a lot of things you can do in there.

The only issue would be if you want the commands to somehow be driven by the Empeg Player application (the actual MP3 player app that plays songs on the empeg). That's going to be trickier because the player app is closed source. There are still some things that the Kernel can do to detect what's going on while the player app is running.

What *exactly* did you have in mind?