I was able to do this mod to my Incredible 2. I was able to plug in the charger and test the points on the back of the phone to determine polarity for my mod.
I am now trying to do this on my Droid 3. Only issue I am having is that when plugged into the charger the leads are set up like so.
1 2 3 4
[ ] [ ] [ ] [ ]
Now testing across leads 1 and 2 I get 1.6v with #2 being the positive lead. Now after more testing it seems like #2 is the only positive lead??? can this be? Am I testing it wrong?
Motorola Droid 3
HTC Incredible 2