Buy a dildo with a suction cup. You may need to tape it down with duct tape because your butthole has stronger muscles than a vagina, so the suction cups will pop loose often. Find something in a good position to tape it to. A weight bench or a chair you can straddle comes to mind. Prepare your body and dildo. Lots of lube, go slow. And clear your mind. I’ve had success 2-3 times and lots of failed attempts because I couldn’t dedicate the time to it. It won’t work like you want it to if you try to rush through it. Once the stars align, your dick will pour like a garden hose.
Dated a girl that would lick my ass then use a finger an make me cum she ever touched my cock it was awesome. I've never tried to make myself Cum that way.
Whether a dildo or an Aneros, patience is the key. Could take a half of an hour or so. But so Well worth it !