Oh, and check this out if you have not...

http://www.diyautotune.com/tech_articles/megasquirt_idle_tuning.html

Gives a better idea of what you are trying to accomplish using idle advance (though it does not mention that actual setting, same thing I think)

Edit: And this:

http://www.msextra.com/doc/ms3/Idle_Advance.html

via above link: "In general, the most stable idle is reached by decreasing the idle timing, and increasing the amount of air entering the engine (using an idle air valve or similar). As such the idle advance timing should be as low as possible while retaining a smooth idle. Since less timing is used during normal idle conditions, as load increase, the timing should also increase to counteract RPM decrease when the load increases."