WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: 12 Volt Socket
Courtesy of VOLVO CARS OF NORTH AMERICA.
Remove:
the rubber underlay (1)
the gear selector panel (2) by pressing in the lugs and removing the connector.