Is there anyway to use B&D gripmates without the plastic inserts?

Hello, I bought 2 black and decker gripmate clamps a while ago at a yard sale and only today I found out that there is supposed to be inserts for them. You insert the gripmate into the plastic piece and you insert it into one of the bench dog holes on the workmate and it works as a holdfast. Would it be possible to fabricate something out of wood to function as the plastic bit?
Here is a picture of the plastic inserts and the gripmates.
https://s3-us-west-2.amazonaws.com/usedphotosna/42675646_934.jpg
And here are what mine look like, I also took pictures of my workmates because I felt like it
http://imgur.com/a/t9sp5

Maybe you can cut down the tops on these and drill/cut through to create your own set of inserts. Would probably save a lot of time and effort. The price isn't bad either.

http://www.amazon.com/dp/B000QE7E4U/?tag=atomicindus08-20

Free shipping on the Ebay set -
http://www.ebay.com/itm/Black-Decke...-010-4-4-Pack-New-Free-Shipping-/281085623633

I made something similar to that a few years back to adapt the hold down clamps from my mitre saw to use on my workmate. This was really quick and nasty so it's not pretty, but it does work ok.

I started with a dowel just a bit bigger than the dog holes in the workmate (from memory I think it was a piece of handle from an old garden tool), and then I rough shaped it with a rasp so it was a taper fit into the dog holes.

I then drilled a hole though the center so that was a tight fit for the post of the clamp, and finally I cut a thin slot in the side so that it could contract and wedge tightly onto this post.

Basically I just push this adapter up from underneath the workmate while I push the clamp post in form above. As I tighten the clamp on something, it pulls the taper tighter and it hold the clamp pretty well.

Hopefully this gives you some ideas. Your clamps are different, but perhaps something like this can work for you.