Here is my attempt at converting a standard ENO DN to use a bishop bag.

This started with an ENO DN that had already had the buckle and strap removed.

Very carefully, with utility knife and scissors, I cut the existing bag off.

I was unaware that the inside of the bag already had a backing strap. This was a happy surprise.

I had my wonderful wife sew around the edge to reenforce the strap to bag connection. Then used a punch from a 1/2" grommet set put a hole in the middle of the strap (no pic, sorry). A quick pass with a lighter and the edges of the hole were melted and won't fray.

Then I pressed in a 1/2" plastic grommet. I choose a plastic grommet because I thought that brass might snag and hear other bags when all packed together and hiking/traveling. You can see the stitching my wife did from the outside.

I untied the knot from the rope at the end and feed it through the grommet.

Not really sure why the knot is there, but I retied it and attached the carbiner. Here it is complete and stuffed back in the bag.