I've mentioned a few times how easy this is and how cool of a feature it is, and was asked to do a tutorial so ...
I found a free thrity day trial of a screen capture program and did it.
This program runs the audio a little behind, but wudya want for free?!?
Anyway, hopefully it helps someone understand how capable the ACW is in certain situations.
http://audiomastering-online.com/stuff/ACW_Tempo_Map_creation.aviIt's a 10 meg avi file
The audio delay does make it a little disconcerting when trying to click on the '1' of each measure, but in real life it will work very accurately for you.
enjoy. (I hope)