Quick update:

I think I've figured it out. I had to watch Mosq's video a few times on this particular step but I set up one of my shamans and success.

Basically, when I spam the space bar (it can be anykey, just whatever you want for your "DPS SPAM" key) it interacts with target and cycles randomly through my shaman abilities. Oh, hell yes!

I'm debating if I should take chain lightning out of the rotation because being a random cast its not always going to cast when at full maelstrom weapon charges.