Thanks a lot, Jason!

With your explanation I was able to get these six buttons to work perfectly :-)
The Select button and the Play/Pause button are using the same code, though.
My goal is to find the right code for the "new" Select/Center button that allows an application to distinguish between both.

It's for an ATV2 - as you guessed correctly.
I'm running XBMC on this thing which assigns different functions to the Play/Pause an the Select button.
I'm aware of the fact that I could teach the ATV to use a different remote and I will do that as a "last resort".
Still it would be nice to figure out how to clone the original Select button on the Pronto :)

Sebastian