The hood on the E32 is mechanical as well...but getting to the release in the car with a dead battery is next to impossible with powered locks. There is procedure you can do by taking the left kidney grill off to access the cable and open the hood...just hope that the OBC alarm isn't coded else the alarm will sound while you're doing this and get's annoying after the first few moments.
Here are some other ways people have come up with to open the hood remotely:
http://bimmer.roadfly.com/bmw/forums...3591248&page=1
http://bimmer.roadfly.com/bmw/forums/e32/3701724-1.html
The emergency/manual unlock procedure involves one of the front doors...don't know which one cuz I've never had to do it. Basically, you put your key in, turn it while lifting the door handle, and you'll feel a little knotch in the handle. Then turn the key some more and the door pin can be unlocked manually. This will not work if the car is deadlocked or doublelocked. The only problem is, you have to re-sync the door locks, else that door will not lock with the rest of them. To do that, you basically lock it in the same manner you unlocked it.