Yup!
It took (and is still taking) practice though. It's one of those things you definitely have to make your body adapt for.
Most males are so used to achieving climax by penile stimulation, it takes a lot of time and effort to re-wire the brain to accept prostate or rectal stimulation as the sole cause.
I have an Estim kit, and an ElectraStim Silicone Noir Sirius Prostate Massager. But the trick for me isn't the Estim.
The Silicone Noir for me is almost the perfect prostate stimulation toy, even without using electro stimulation.
What did it for me was applying my wand to the base of the toy while it's inserted, with the vibration set to such a frequency. that it provides a tickling hum straight to my prostate.
If I'm aroused enough, that'll give me a wonderful prostate orgasm.
I still have to stimulate my penis a tiny amount to get me close to my climax, but I'm noticing I'm requiring less and less of it.
In my experience, a prostate orgasm is totally different from one induced by penile stimulation. The build-up is much longer and more intense. Ejaculation more is like one or two big gushes in stead of the pulses I get when climaxing from stimulating my penis.