I have beaten Metal Gear Solid more times then i can remember on the Playstation, and I had been able to get past the torture sequence without having to do anything weird to push the circle button fast, but I have spent the last couple of hours repeatedly dying at this part when I play it on my PSP.  I think it's because of the ability for the Playstation controller to vibrate during this part that makes it easier.  Also the buttons on the PSP behave a little bit differently (I'm using a PSP-1001), and I think that the face buttons might not be as sensitive as they are on a full sized Playstation controller.  I guess that I could just export my save back over to my PS3 and play it with a real controller, but that would be admitting defeat.

I have the same problem.

I've tried mapping two buttons to function as circle so I could use two hands, that doesn't work.
I've tried mapping all the buttons to function as circle, then proceeded to mash the shit outta my PSP and that doesn't work.
I've tried telling Ocelot to go F**K himself, but surprisingly that doesn't work either.

I refuse to play on PS3 as it looks bad, and that would be admitting defeat like you said. Any help would be awesome.

Meh. Has nothing to do with vibration, it's just as easy on both. You just got old or something.

Maybe you're holding it wrong? Left hand as normal, rest the whole thing steady on your lap, put your right index finger on circle, jerk rapidly.

MGS came out 11 years ago... God, maybe i am just getting old.

I did this on the PS3 but I'm not sure it would work for the PSP: I wrapped the non-writing end of a sharpie with a white t-shirt and slid the side across the button repeatedly. It worked really well. I noticed some of the black from the controller rubbed off onto the shirt though. I chose a sharpie because the ends are very smooth and I figured it would not scratch the controller with some cloth in between. It left the controller in pretty much the same condition.

Sounds funny that you have to do anything but press the circle button.

It seems crazy to me that you have to devise all of these crazy solutions to something that should really not be a problem.

Insanity.