Becky I am sorry you had to go through that as a child.
My son goes to a therapy clinic called the Child Development Institute. He sees kids there in the waiting room, he does a social skills group with other kids, and some of the kids there are at his school too so for him it's just normal. They don't use the word therapist there either, he goes to see his "friend," Megan.
All great for my little guy with autism who's been receiving intensive therapies forever, right?
My point is that therapy doesn't have to be a secretive thing that makes the kid feel that something is wrong with him. My guess is that you felt like something was wrong with you because of something your mom said about it, or it was isolated in an office, or because your parents didn't talk about it at all and that made you feel weird.
If you are worried your child will feel labeled you can say the therapy is for you. That is true too. You are learning techniques for your child, you are learning more about your child.
The play therapy we've done in the past used dolls and props. It just looks like playing. It's a safe way to work through scary emotions because the doll is feeling/doing it. I'm kind of scared to do it with the poop issue too but I couldn't even tell you why. I told myself if we don't make progress I will and so far we are.
If you want to try the scheduled sitting you can make a picture schedule that shows three activities. For example, first a picture of say, reading a book or having a snack or some activity, the next picture might show a clock and toilet, and the third thing should be a preferred activity--playing trains or watching his favorite show or whatever he likes best. When it's time to sit you can use a timer--for me it feels like too much pressure. When time is over it's over. Praise him for the waiting--NOT the product. Then on to something fun.
We started doing the scheduled sitting about 20 minutes after dinner and it's starting to slowly work. He now poops at roughly the same time and is having less skid marks in the underwear and more poops in the toilet. I think he is slowly starting to be less scared.
I have heard the book "Everybody (or Everyone?) Poops" is a good one but I haven't gotten it yet. http://www.amazon.com/Everyone-Poops.../dp/0916291456
Do you know his poop cues? My son and I sometimes watch thomas the train songs on youtube and he would get relaxed, and then I would feel him squeeze his legs as he put the poop up back inside his body. I also can tell the "poop face" look, strained kind of look. I would tell him "let's go to the potty," and he would get panicked and say NO!! So I started saying, okay, we'll go in three minutes then. And then in three mins I wouldn't ask him, I would just tell him it's time to go and give him a choice. They love the choices, it gives them some control. I would say okay time to go, do you want to go on the big potty or the little potty? (Baby Bjorn potty) and he would choose.
Just keep calm Mama. It's gonna work out. Ya gotta be relaxed. Take it from someone who knows. They can sense our freaked-out-ness and it makes it worse for them. I hope my saying this doesn't offend you but I think you should stop with the promises and emotional conversations about the whole thing, it just ramps everything up. Don't talk about it, you both know what's up and all the emotion just clouds the issue and makes it bigger. He holds it, just say okay maybe next time. Keep it short and light. Don't make it the end of the world, that is scary.
Last of all I have some links for you from the Berkeley Parents Network, lots of anectdotes from moms and there is a little piece in there about play therapy too: http://www.amazon.com/Everyone-Poops.../dp/0916291456
It's gonna be okay, I promise!!