hm, practicing got me pretty good at those jumps with one hand. i guess thats all i can tell you =/

Aren't jumps hitting 2 arrows at once repeatedly? If they are, I'm not 100% sure how to deal with them. I sometimes use my middle finger for both the up and down arrow key at the same time. If you know the song well enough, you could use the index for the down arrow and the middle finger for the top arrow. When I do that, I use my thumb for the left arrow and ring finger for the right arrow. Hope that helps.
Long tip, ain't it?