I don't think of enemas as a "Gay" thing. I am not so sure what a “Gay Thing” is.
I have been married for most of my life (to a woman), however I have play on the other side of the fence a few times (yes my wife knows). That doesn’t make me or anyone else GAY. If you eat a salad does that make you a vegetarian? Will going to church make you a Christian?
People worry way to much that something is going to label them as "a _______" (fill in with anything).
Finding someone to have enema fun with should be no different than anything else that the two (or 3,4,5) of you enjoy. If no sex is your rule then lay it our before hand and stick to it. I have said and heard before “This is my first time at this so I am not sure what to expect”. Above all else be honest to yourself and those around you.
As for finding someone to enjoy enemas with can be as simple as having your equipment in plain site when friends come over.