Using Logitech Z-680 without pod

I am a complete newb when it comes to this, so bear with me. I am trying to learn as much as possible about hacking my Z-680 amp, so that I can use the sub and speakers with the original amp without the pod.

This page: http://www.diyaudio.com/forums/chip-amps/26714-logitech-z-680-a-6.html#post615079 down at the bottom has the best explanation I've found. But being that I'm a newb, I can't figure out how to actually do step 4 and 5. I want to connect it to my PC. After much researching on how 1/8 TRS jacks are wired and such, I think I sort of figured it out, but I want to be sure. I'm assuming that I can use 1/8 TRS plugs to connect to my sound card directly....

Any help would be greatly appreciated.