early missile: temple assembly site
When you enter the room from Collapsed Tunnel, head along the left wall until you find a small pillar. Just before this pillar is a slope you can walk up. The pillar can be landed on by using the slope to ghetto jump.
First make sure you're looking in the direction of Dynamo Chamber (like the video), then run left at the slope and time your jump so it adds to your height. Once you line up with the pillar's center, try to push yourself onto it. It's not easy; you'll need a perfect ghetto jump to do it.
After you land on the pillar, jump to the ledge now in reach.