[Mark44]

The Owner's Manual for my 997.2 shows a different method, which might also apply to the OP's 997.1. Here's what my manual says (Emergency unlocking of the luggage compartment lid, p. 262 of Owner's manual):
1. Use the key to unlock the door.
2. Remove the plastic cover from the fuse box. (It's in the driver's-side footwell.)
3. Pull out the positive terminal C (red) in the fuse box using the plastic gripper A (yellow).
4. Use a jumper cable to connect the positive terminal of the donor battery to the positive terminal C in the fuse box.
5. Use the black jumper cable to connect the negative terminal of the donor battery to the door arrester D.
6. Press button 2 on the remote control for approx. 2 seconds to unlock the luggage compartment lid. The alarm system is switched off.
7. Disconnect the negative cable first, then the positive cable.
8. Push positive terminal C into the fuse box and push on the plastic fuse box cover.

I've recently done some work inside the doors on the 996 I previously owned as well as the 997.2 that I currently own. In both cases I disconnected the battery so as not to trigger the airbags. I put a block of wood across the body latch point to keep the hood from closing all the way.