tadaaa ok, but i'm very tired...
do you mean the airport düsseldorf or weeze? i don't know exactly where the hostel is, but if you go by train you need ~15 minutes from the ddorf airport to get to the phillipshalle.
it's a german site but there you can see the number and direction of the trains or bus you have to take: http://www.rheinbahn.de/opencms/opencms/html/de/index.htm?size=gross
edit: well, i thought it works but doesn't