As this one also has the iTunes library and the connection to the stereo, I was using VNC to connect to it and to start and stop iTunes. Of course that is cumbersome.
So I googled a little on "applescript" and "iTunes" and found this wonderful site.
Using the information on it I was able to come up with this script, that I saved as playTunes.scpt
tell application "iTunes"
if player state is paused then
play user playlist "a_Ungespielt"
It will play the contents of a playlist called "a_Ungespielt" if iTunes is paused and stop playing otherwise.
I can now just log into the mini and start/stop playing with "osascript playTunes.scpt".