Ah, ya. I was thinking you were going to use it for a PC and you could make it work that. Way it is, as said, you will only get 2 channels since that's all your TV will have coming out.
Now if you are really into doing electronic's fun, you could make a small box with volume control for each channel and do a very cheap stereo - > surround circuit.
This is what I would do off the top of my head and really only need a small breadboard and some caps and volume knobs if you wanted volume control. lol.
You will have a Left and Right source coming from the TV.
I would take both signals and put them together to sum them for the center channel. This would only need a couple resistors.
I would take the same summed signal and run it through a low pass filter circuit. this will give you the sub channel.
I would then take the left channel and that goes to left front, same with right, goes to right front.
Now the two rear surround speakers would be the challenge on what to do. you could build a simple delay circuit by a few ms to give it a kind of echo effect, or just a high pass filter and filter out the highs so you only get the high chhhh's and chaaaa's from the rear, or both.
Probably way above your head on what I said, but just saying you could with some resistors, capacitors, breadboard and volume knobs, you could make a sim-surround box.