I had the idea in my head, but seeing a schematic in an article of Machine Knitting Monthly helped me visualize.

I used Tamm Kitty and T-3 on my Singer 321. It’s taken me 4 hrs and I still have the crochet edging to do. I suppose it would be faster if I could manage the blocking wires better and if I had machine sewn the seam. I like the flat seam though. I will have to invest in a standing magnifier if I’m to do this seam often with stitches this small!!! LOL

All total it took about 13 hours, 11 of them being the crochet work on the trim. I used a B hook and a basic trc shell stitch.