actually I did figure it out by myself. I was pretty surprised to find out that you do not have to do any access / right management settings to give iPortal access to the users of your AD.
All you have to do is to go to ..\EAPowerTools\iportal\udc and type in all the neccessary informations.
e.g. in iportal_attributes.csv you would have to add a new line.
I guess that udc stands for user directory connector and therefore you have to write in the name of the UDC to your AD as it is named in the QMC.
Furthermore you have to update the content of the other csv in the folder too. But those are pretty self explaining I think.
this is working for me:
mmuster, udc, ABC
mmuster, app, hub
mmuster, app, QMC
(ABC is the Domainname)
Feel free to post you configuration if this does not help.
All the best