|N version||1.4 and later|
Run to the left. You should just barely avoid all the thwumps. When you reach the end of the platform, jump, and wall jump back to the platform just above the one you were running on. The thwumps should just be coming back into place, forming a solid floor to run on. Run to the jump pad on the right, and launch to the one ways at the top. Jump to a bounce block, and jump down into the shaft at the left. Fall the length of the shaft, and wall jump when you hit the swtich. Wall jump out quickly, and the rocket should blow up on the inside of the wall. Fall down the left wall, and do a quick wall slide so you don't die on impact. Start running underneath the thwumps on the bottom. Get in between two columns of thwumps and jump over the zap drone as it comes by. Run all the way to the end of the row, to the set of locked doors. The thwumps will all miss you. Grab the switch, and try to jump off the thwump to the wall on the right. Slide down the wall to the door. Watch your ninja get demolished by the floorguard. Have a small chuckle if you believe it is in order.
See here for a demo.