I could post a code snippet soon, but the sample you refer to is of a KeyCapture event.
As I use the free license I cant use that API..
To my knowledge, Keycapture API is only way to override default action of the device back button.
Let's wait to hear Motorola voice.
We experience the same issue when upgrading to version 4.0.0, a bug has been raised by for the issue.
In the end we disabled the back button by editing the RhodeActivity.java file.