Could do it a couple different ways. Assuming your probably want to use the mixer as a monitoring device (speakers/headphones) at the same time, you can do a couple things. First thing is the cables. Probably wanna run to and from the stereo line in on your sound card. Hit Radio shack or something, and get (4) RCA to 1/4" mono cables. Then get (2) stereo 1/8" to RCA adaptors. Plug the adaptor into the sound card line in and line out, and hook the RCA side of the cables into the stereo 1/8" to RCA adaptors.
Easy way:
Going from the mixer to the sound card could be through the inserts on each channel. Easiest thing to do. Just plug the cables coming form your sound card line ins into the inserts of the channels you want to use. It will use the inserts as direct outs after the mic pres.
Hard way:
You could also probably use the busses if you are gonnna use more than 2 mic inputs at a time, or wanna set and forget all 4 of them if you're gonna hook up a few mics and a bass guitar or something and don't wanna mess with settings/cables every time you switch an instrument to record. (more noise if you run through the whole bus though)
Hook the line in to the sound card to sub group outputs 3 and 4 and have only 3-4 clicked on all your mic channels. Then hook the line out form your sound card to a stereo input channel and set it only to 1-2. Hook your speakers/monitors up to the 1-2 subgroup outputs and set the headphones so you only hear bus 1-2. You can monitor what you're recording through the computer. Mute input channels not being used. Problemn with this his hooking it up wrong or hitting the wrong subgroup buttons. Wrong move and it's Feedback-o-rama. Gotta keep the inputs and outputs from the sound card separated or your ears and gear won't be pleased.
