I've gotten this down to a science now. It's very simple, but they key is to KEEP MOVING. Jump a lot once you're past the large rock, it'll keep the rockets from doing more than minor splash damage, and the guns will miss about 50\% of the time also. The other trick I've found useful is to be running about 15-20 feet from the wall of the power plant, this will negate any splash damage from the rockets. If you do everything right, you should make it to the power plant with at least half health or more; throw some proxies around the doors if you're a Technician then work your magic with the C4/nuke.

This tactic works best with Technicians or Stealth Black Hands with nukes.