Found this idea on youtube. It works!!!! Piston seals just snap in place. No soap, no boiling water, no problem. They guy in the video uses the cap from a bottle of locktite which I didn't have so I searched around my house and ended up using the cap from a standard Sharpie permanent marker to install the piston seal on my air hawk. The Sharpie cap is just a little to small to be perfect but worked well enough that I stopped looking for something better.
We have a similar cone that we use when assembling a D.C. Motor, it assists in pushing the brushes back into their holder so that the armature can easily being installed. Otherwise it is a monkey with a football.Michael :- )