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: Drilling Out Mounting Screws
Courtesy of VOLVO CARS OF NORTH AMERICA.
Drill out mounting screws
Center punch the screws first.
Drill, first with a 3 mm (0.118 in) drill bit, then with an 8 mm (0.315 in) drill bit.