At least I hope the title of this thread can be carried with the few pictures I'm posting.
easy.jpg It's just an O-ring cockring between the Bathmate and the Vacu-vin. It can take a moment to get it working, but it works.
attached01.jpg Material removed inside the Vacu-vin cork so it'll slip on the Penomet easily.
thering.jpg Just shows the ring close to the Bathmate valve.
bored.jpg Weird closeup somewhat showing how the cork fits on Penomet. (Like a glove!)
corked.jpg The cork top attached to the Penomet, ready for action!
For Penomet, you remove the top lid of the cork and bore the excess material away. When you've done this, lightly squeezing the cork and attaching it is very easy!
When the cork is on, you're still able to release the pressure easily. In certain way I think it gives a slight more control over the amount you'll release, as in if you want to vary the vacuum.
For the Bathmate, this is one of the easiest ways to get the job done; a cheap donut style cockring. As long as there's some width to it and it's not too thin, it'll do the job. In my experience, this O-ring type solution is the quickest and easiest; and give your imagination room, you'll find you can substitute the ring with other methods.
Of course you can opt for removing the whole valve assembly, but I have the Extreme model for the moment and I like to keep it stock. (Of course the stickers is coming of though, but's that given, just wear and tear.)
I think I paid less than 5 USD for three of those green rings pictured. (Actually glow in the dark cockrings.)
The same O-ring type solution does work with the Penomet as well!
I hope this gives some clarification to the whole business about Vacu-Vin modding.
"Yet another way", just using the cork top!
I was just playing around and noticed that this way works as well. As the round hole on the cork sits quite well on the pip, it's not very difficult to get the pumping going.
Just be sure the pip is on the middle! Going really hardcore I noticed that the top wanted to get inside the pumping tool, but overall it worked well.