Wrong forum, this is for 94-02 P38. However, can you get to the starter main terminal from underneath and put a jump lead onto that? Do you have 12 pin or split towbar electrics? There's a permanent live connection on that so you can feed power into that if you've got it. Rumour has it that you can pull one of the side repeater indicators out and connect power to one of the wires (yellow I think) on that but I can't see that being the case. Maybe on a US spec car with side marker lights?