It took almost three months before feeling the glans squeeze inside for the first time. Extraordinary feeling too. I'd been trying too hard in every sense of the word; needed to reduce the pressure. Do it once and you know you can do it again. Psychology y'see.
Next problem was not being able to get the pressure up, presumbly because of constricted blood flow, so no in/out action for me. I wasn't too fussed because of the fun to be had just pushing it in a few times.
There was also the worry of it slipping out once it was in. It is only recently that I worked out that if I pushed along the shaft from the root towards the head over and over again, one hand at a time, it would stay where it was. Still no in/out action though, not enough lubrication.
Tonight I found a solution to the slippery problem. Instead of using extra virgin olive oil (seemed appropriate somehow) as usual I tried using vaseline The one-way push-ups along the shaft gave a firm but not over-inflated tool to work with. It wasn't long before much to my surprise 'that' sensation welled up and several million potential prime ministers/nuclear scientists etc came to a messy end inside a black hole.
So there.
I've done it.
I know I can do it again if I want to. More psychology.
Will I do it again? Don't know. It's the worry about the UTI possibilities for one thing. Also, it's not a good thing to do for any length of time because of the restriction in blood flow around the penis. If the blood can't get out of the penis the cells die! Twenty mins is the limit. Of course, not everyone will have the restriction problem in which case there's just the abnormal twisting, stretching etc. to deal with.
So maybe on special occasions - it would be cool to film it

Just for the record, I only have an average-sized weapon to work with. if you want proof take a look at http://www.xtube.com/play_re.php?v=jQf7gtfqZ7j which is NOT a SF vid by the way!
I reckon any average-sized guy can do it if he wants to. It's all in your state of mind.