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 Pressure Regulator And Screws
Courtesy of VOLVO CARS OF NORTH AMERICA.
Remove:
Both screws on the pressure regulator and paper under the pressure regulator to catch any spillage.