There is no formula for converting dpns to magic loop. They are just two methods to arrive at the same results. This is why you will see very few patterns actually written for magic loop. Any sock pattern can be used for any method of small circular knitting (magic loop, 2 circs, dpns).
When you say that you have holes on one side of the heel, do you mean along the edge where you picked up stitches??
If so, I used to have that problem too until I experimented a bit with how I was slipping stitches for the heel flap. What works for me now, and I don't get holes on either side anymore, is this:
The first stitch of every row is slipped, but what the next stitch on the needle is going to be determines how the stitch is slipped. If the second stitch on the needle is a purl, you will slip the first stitch purlwise with the yarn in front. If the second stitch on the needle is to be a knit, you will slip the first stitch purlwise with the yarn in back. Then on every row you will knit the last stitch. The two slipped stitch edges will NOT look the same - one will look like a braided chain and one will look more like little knots with strands between (hard to describe) but once I started slipping stitches like this I've had no more holes down the edges of the heel flap and when all is said and done, both sides look the same.
Hope that helps.