Hi skeet,
I'm writing from memmory so please bear with me if it's all wrong. It's tricky, that much I remember

.
You have two plasma boxes, right?
If you arrange the first one just NE of the one the Kaboom is circling, the Kaboom will now circle both boxes. With careful timing: move the lowest one out of the way and then just NE of the other one. I don't remember how many times you need to do this, but hopefully you get the idea. I think I remember something about being careful not to blow up any of the boxes.
I hope this helps you out. If not come back and ask again and I can replay the level and help better.
Good luck,
Mette