I don't know what kind of inputs/outputs your mixer has but basically you've got 2 choices. Either take the stereo mix out of the heaphone jack or else use the camera connection kit and output via USB?
If the headphone jack then the issue will be sending all your separate (8) tracks down a single stereo jack. You can get round this by panning each instrument hard left or right and then recording them in groups of 2- ie it will take 4 passes to do all 8 instrument tracks
Hope this help
Jez
