1. Walk outside near the generator.. see these 2 prongs sticking out from the walkway??? Walk on to one of those and stand on it... wait a while...
2. while a cart goes to refuel or whatever, this tube sticks out underneath you! Get on top of it and CROUCH!!
3. Stay crouched! Wait till the tube retracts, it'll drop you into a ledge, wait here...
4. Stand on one corner of the ledge (DO NOT STAND INFRONT OF THE TUBE)
5. When the tube has retracted, quickly get inside the tube and follow it till the end till you reach this small room (the generator room)
6. QUICKLY Destroy the 4 tubes on the wall (2 on each side of you) this will bring down the red forcefield around the generator.. Destroy the generator!
7. Keep waiting now because you will no longer die while the carts refuel... wait fort the generator to come down to floor level.. stand on it..
8. the next time the generator goes up, it will take you up also into the room that the carts come into
9. Climb up one of the supports on the sides of the big room
10. Wait for a cart to stop underneath and then jump on it and Crouch
11. Just remember... you DON'T have to ride the cart all the way, you have to jump off at one point....
Hope that helps