I'm one o those guys preferring to figure things out myself, but these ones is outta my comprehension.

FIRST:
I downloaded a scenery for airport ESSA (Arlanda, Stockholm, Sweden). NOTE: The add-on is for fs2002 and I'm using fs2004. Is that crusial?
Anyways... The scenery is there all right, but as you might imagine the AI aircrafts are taxing on the grass, through the buildings and... phuuu.
I figured I had to edit the AI or the airport itself in TTools or AFCAD... but... uhm. I can't figure out how. Is this perhaps because the scenery is from 02?
Someone please tell me how the heck I get those planes on the taxi- and runways!