Sub hook up question....

[ls7z06]

I am building a little 2.1 channel system in my den and need some advise on hooking up the sub.

My room set up makes it impossible for me to run a single LFE RCA type cable from my receiver to my sub's LFE input. Can I just run a set of speaker wires from each of my front L and R speakers to my sub's left and right speaker in connections? Does it matter if my speakers are 4ohm speakers?

I am using an Onkyo TX-SR806 as a preout to an Emotiva UPA-2 which is then hooked up to a set of Polk LSi9's using Monster flat speaker cables which I had to run under my carpet. Now I need to hook up a little Polk Micropro 1000 and I do not want to run a fat LFE cable under the carpet to get back to the receiver. SO I am hoping I can just run speaker wires from the back of my LSI9's to my little sub.

Any advise is appreciated!