Once it's on it's on, it can only be reset by plugging in. I have the kit to do it but I'm a bit far away in Fife (not impossibly so, if it comes to it).
Looking at the map I can see there is somebody in Dumfries with the VIDA-DICE kit to do it
http://www.volvoforums.org.uk/showthread.php?t=136759 The best thing would be to contact him.