Nice grip, non-slippery and will work (at least it did a couple of times I tried it), also works in clearing off salt and build up.
For some of the bigger o-rings such as the housing's main o-ring, you may be able to just use your thumbs to push two segments towards each other and that will pop the intervening segment out.
the main o ring and the port oring are not the ones i am worried about. It's the ikelite sync cord orings. I now use a combination of pushing them out with my fingers, and then stickig a metal dental pick between the o ring and cord (to save it from being scratched).
In the sync cords, the screw cap is a little in the way to do this comfortably...