After building the frame and sinking it in the ground with some concrete and cable anchors, I strung a stainless steel cable up and across the top. This line is what I tie the vertical lines to. The top horizontal cable can be lowered to pull down the vines for harvest.
The cable is fished through an eye hook in each corner.
Then down the posts and attached with some creative hardware
Disposable poly lines run every 18 inches or so. These get cut down every fall and cost about $3.00 total.
An eye loop in the cable to hold the poly lines, and stakes hold the lines in the ground.