Claypool's strumming technique isn't really too hard to learn. If you can strum a power chord, which is mostly what he does (like tommy the cat, john the fisherman), then just pick a simple pattern with 3 or 4 power chords, and repeat it over and over strumming up and down. Just don't dig into the strings too much, if it hurts you probably just need to lighten up.
The hard part is alternating strums with slapping lines and keeping it in time. Slap a couple octaves and strum a couple power chords afterwards, and cycle back and forth. It's a little tricky to get the timing right and make it sound good, but once you can do that you can pretty much play anything Claypool does.
And then you can sound just like Claypool, which isn't as useful as you'd think
