Thanks Bob,
I tried also on my iMac in my office right now. As at home, browsing for the .xml file using "change" in "preferences/Itunes", then clicking "open" (or "select", whatever it is) does not provide any result, even after relaunching. Of course, the option access ituns library is flagged. I'm frustrated. There must be smth with Itunes blocking access to the library, but everything runs fine with Pure Music, Amarra, Decibel etc.
Please help