I have a LG VX 8600 (the Chocolate Flip Phone) and I just took apart the audio connector that came with the phone. I believe all pins are are the same as the 8500 listed here.
The connections I tested revealed the following:
1, 11, 18 => GND
14 => L or R Audio
15 => L or R Audio
17 => Mic In
Updated.
Thank you!