It is NOT necessary to have an erection to have an orgasm. The erection is controlled by the parasympathetic nervous system and the orgasm and ejaculation is controlled by the sympathetic nervous system. You can have an orgasm and ejaculate by stimulating a flaccid penis.
In school (I have a BSN/MSN), in neuroanatomy, we used to play the game "Name the Lesion." Signs and symptoms are listed, and then you have to determine where the CNS lesion was. It's the same thing here. One must know where the lesion is in order to determine exactly what will work for you. Alternatively, if you don't know the lesion, just experiment and see what works for you. After all, since you are the patient, you get to do all the experimentation!
For some men, electro-ejaculation will work. For others it won't.
As I posted in a previous thread, men seem to exaggerate (sorry guys) about how much stimulating their prostates have to do with their "extremely massive fluid outputs and ejaculations" and orgasms. It's gotten to the point that it's like "you girls have a G-spot, and I have a prostate and you can't imagine how good it is." The men are over-rating it and doing a G-spot/prostate one-upsmanship. I'm not saying it isn't extremely good, but in their descriptions, they are elevating it to something incomprehensibly amazing. I have been with enough men and seen enough "prostate enhanced orgasms" to know. (Maybe someone like CougarDomme can chime in to bring a little objectivity, additional medical information and to corroborate this.)
Check out my post in this thread:
Anything but Enemas Prostate massages newbie question Reply #13 2008.12.08 21:32