Figured I'd bump this as I've wanted to do the same today and found out how to do it!
1. Engage your “object grabber”.(not your “regular” grabber, object grabber has two boxes above the hand)
2. Hold down Shift and select all the regions you want. (they will have a yellow border around each of them)
3. Hold down command and use the + and – keys (on the numeric keyboard) and you can easily trim and extend them (the ends of the region). NOTE that the increment is based on your nudge value.
4. Hold down OPTION and you can do the same to the beginnings of the selected regions.
The only downside is that you need to hold shift and individually click on each region you cant to do this on, you cant click and drag like you can with the trim tool.
Hope this helps some of you, I know it's saved me a bunch of time today!