Audio out only for K810

[navster]

I've recently bought a cheap audio out adapter (converts it to a standard 3.5mm adapter for headphones) from eBay, which works great for listening to music. What would be even better would be to use it as a handsfree, I can then plug it into my car and have who im speaking to coming out of the speakers. However, the way the thing is designed, it actually has the 2 mic pins visible, so of course it blocks off the mic when I plug it in. I have tried blocking the 2 mic pins with duck tape(!) which covers them up okay, but the mic is still blocked when I try to make a call.

So my question is, what other pins do I need to cover up? Or is this not possible, as the mic/audio out work in unison?

I'm working from this diagram: http://pinouts.ru/CellularPhones-P-W/se_k750i_pinout.shtml