each output of yer soundcard goes into a different input channel of yer mixer.
Use an auxiliar out (or 2) plugged 2 the input of yer mixer... this way u just choose what 2 send (and level) 2 b recorded on yer sequencer...
The only prob is that sometimes the aux send don't include eq.... if given a choice, use post-fader.. (which generally means the sound goes thru all stages.. insert, eq, fader b4 being copied 2 the aux out!!)...
U can also use the monitor out, u can choose what 2 record by doing solo on those channels, but u get the same prob. as the pre-fader auxs... unless it a solo in place...
If yer mixer as more than one master out (ex: XLR balanced outs and Jack 1/4 " TS).. then u are in luck just plug the jacks 2 the input and the use mute 2 select what u want 2 record...
Hope this was clear enought!!
Z