You like what you like, you want what you want. You are an adult and are able to make these choices of your own free will. Understand that you are not alone and your "issues" are shared by probably thousands of people.
Everybody has their own thing, and that's okay, so when you are looking for someone, be completely honest. Write out your list and tell the person with whom you are speaking exactly what you are looking for.
And before you get too far into any conversation, just tell them like it is, exactly what you want. Chances are, like I said, there are many others out there who like you chicken out or are afraid, or whatever who are in fact, looking for exactly the same thing you are, just an enema sir, and nothing but the enema.
On top of being honest, don't hem-haw around about it either. Give it to them point blank, that way in case they are fine with just giving and receiving enemas, but are hoping he might be able to talk you into something else, he will know immediately that your mind is made up and this is what you want and what you seek. It will save you both a lot of time and energy once both of you are on the exact same page.
So three rules:
1) Be Honest
2) Be Simple
3) Be Firm
Hope this helps. And good luck on your search!