First, you must make sure to play the game with Jumper Pak (Playing in Low-res mode with Expansion Pak is not enough)

When you are in the Engine block room, you have to run all the way to the end on the right.

To to the skip you have to hold A and R at the same time and then strafe to the left.

Then you must jump get on top. You need a good angle to do this.

I hope my explanation makes sense, good luck!