Uuups... used config
JBoss IDE 2.0.0 Beta2
JBoss would be 4.0.4 but that shouldn't matter since I'm just configuring the packaging process.
SOLVED (sort of)
I tried it several times and finaly after a System Reboot and with plenty of 'Apply' clicking inbetween the configuration it worked.
Dunno how to explain this, but it's deffinitly no general JBoss IDE topic.