I figured out the one jump method, but I don't know how to do the double jump method that takes you all the way to the end (the WR run uses this method). Thanks

There are two known methods, one that the full game run uses and an alternate version. I'm not sure how the full game runners do it but the alternate version jumps a frame earlier than the 0:20 strat and holds left on the same frame, for 4 frames. That will always break you through.