I did a short highlight talking about setting up the volcano jumps, I hope it might be helpful for people who can't use the LUA to help figure out the best setup.
And in case I didn't explain it very well there, basically: For the first jump, at the beginning of the level, your height on the rock is the most important thing. You have to be either 1 or 2 pixels from the top of the rock to make the jump, and watching your shadow is the best way to tell your position is good. If 2 lines of your shadow overlap the lava below the rock then you will be too low to make the jump.
For the second jump, the easiest way to do it is to line up all the way on the left of the rock, another 2 pixel window, and jump straight up. You also need to be just as high on the rock as on the first jump.
I hope that helped clarify and I didn't just make it over complicated.
