WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Filler Pipe
Courtesy of VOLVO CARS OF NORTH AMERICA.
Remove the lock ring from the rubber gaiter.
Press the rubber gaiter and filler pipe into the wheel housing.