Hello,
We trained Cora, our beautiful Cherry Head Conure, to "poop" on command, but only first thing in the morning. That said, she still poops when she has to throughout the day! So, if you have a bird, get used to the poop!
Cora "saves up" her poop all night long, so when I uncover her in the morning, she has to make a HUGE poop. She likes to come out immediately and sit on my shoulder when I uncover her, so I have had more than my share of HUGE Cora poops all down my back! Once I figured that she WAS going to poop within one minute of being uncovered, I would get her to step up on my finger and carry her to the bathroom, hold her over the toilet and say, "Poop Cora!" Since she had to poop anyway, it was a given that she was going to! Sometimes I would have to "tell" her to poop a few times before she would, but when she does, I ALWAYS give her a big, "GOOD GIRL!" and a kiss. I did not "teach" her to poop, I just taught her what the word "poop" means, and give her lots of love for doing what she was going to do anyway!
You will learn to read your bird's body language. They sort of "squat" when the are going to poop. If your bird is on your finger and you see the sign, you can quickly get him/her over a waste can and say "poop." When the birds are with us on the sofa, we can often get them over the waste can in time, if we are paying close enough attention to their body language.
Again, you are going to get pooped on...it's just part of being a birdie guardian. And please never make a big deal out of it when you do...it washes out!