Sure. Here's an overview:
This is the back mounting bracket:
The back is designed to be mounted to two places, but I ignored that and used a couple longer 3D printed spacers to center-mount it. I also used 8mm threaded stainless steel stock for the "bolt", and stainless nylock nuts on each side to hold it all together. I had to drill out the holes in the seat mount to 8mm though - they were originally more like 5 or 6mm.
And here's the front:
The front fit nicely over the square tube, with just some small spacers that I 3D printed - could have just as easily used washers or machined spacers or whatever.
My butt hits the center bar (through the seat) if I sit up, but sitting back in riding position there are no issues. If it ends up really bothering me, I will weld a flat plate to each side of the square tube that sticks up a bit, and mount the seat to that, an inch above the tube.