You can probably use a bunch of splitters and stuff, but that would be pretty ugly. I'd recommend getting the DD-5.1 so you can hook everything up to your PM5.1s. It would probably do what you're looking for.
It's like a mini-receiver made by Klipsch specifically for their ProMedia speakers. Takes a bunch of different inputs and outputs them to your speakers. Also has a DSP to do prologic, equalizer, bass adjust, and some other stuff. Costs about $100, I think. Check the Klipsch website, it's designed specifically for what I think you're trying to do.