Morning Grassle.....I had a look at this duff motherboard of mine and the mic on the mini 9 is totally separate to the webcam. It has it's own tiny 4 pin socket on top of the motherboard underneath the touch pad.
I haven't seen a 1526 webcam so I don't know whether the mic is wired or built into the board but it seems to me that you can simply forget to connect the output from it and all will be well. If this isn't your problem it would help me if you could put a picture or diagram up to give me e better clue.
ps I might have solved my own problem, I think that Dell are using the yellow wire to switch the camera on and off using simple TTL logic. I need to test this out.