Hmm, no offense is intended, but......why? What is the end game here? What would the point be of duplicating the front to the rear? Of course, I will bow to the expertise of those that work in surround, or maybe you have very specific needs that I don't understand, but your whole question raises many more questions for me
On the most basic level, you need PT Ultimate(to handle surround) and an interface that has at least 5 outputs(for your 4.1 target). Then, the final deliverable will likely need to be 5.1(even if you choose to put nothing on the center channel). Maybe more detail will get better answers
