Here's the longer version of my response (I typed the short one in on my iPhone, since you indicated it was urgent...).
What Soundcraft model is your friend using? If you can share this information, we can look up the manuals online and see what connections are available.
Virtually all mixers have balanced outputs on 1/4" phone ("TRS", which stands for "tip-ring-sleeve") and/or XLR connectors. One 1/4" TRS is a single channel, so don't connect it straight to a 1/8" stereo mini plug. One analog XLR, too, carries is a single channel of audio. You should be able to find an adapter that connects a pair of mono TRS (or a pair of mono XLRs) to a single 3.5mm stereo plug. It's not ideal, since the mixer's output is likely the "hotter" professional level rather than the consumer level, but if you turn down the mixer's output level enough this should work. Also, you are mixing balanced and unbalanced equipment, which often works alright but can introduce hum or other bad things.
If the mixer has an RCA output, it's a little simpler. An RCA-to-mini stereo plug adapter should be very easy to find (such as at your local Radio Shack).
If you think you will do recordings a lot (or need better quality for this one recording), you should consider getting a USB or (even better) Firewire audio interface for your laptop. You could then use the professional balanced connections all the way and more than likely get much better analog-digital conversion that what your laptop does with the built-in port.
No, sorry. The idea of the forum is that
everybody can learn from the information exchanged, so I'll only post this in the public forum.
Good luck for your project!
- Martin