I fitted a net a couple of years ago, while messing about with ideas on the XJ.
I had seen
Raingler nets, follow links for pics. and
U.S.Nets.
So went down to local ship chandlers, and they were able to make one for me, with eyes. It was not adjustable however. Sorry no pics.
You can get cargo netting from several sources including lifting supplies and cargo lorry outfitters.
One idea we did work on is using clambuckle straps, like Thule straps, and have them riveted, or sewn together. We found a camping shop that sold clambuckles, and quick realease clips like those used on rucksacks. So it could be possible to fit them to the premade netting, web strapping from several sources for other end if needed. Chandlers do hooks with 360° swivels on them. This would make for a fully adjustable system.
As regard fixing, we wanted to use with seats down and swab removed. We used the seat belt fixing points, and bench seat swab swivel points for the lower points. Upper was harder, we ended up using grab handles, not ideal, though did allow for a storage sacks for soft items such as waterproofs to put behind the seats.
Hope this helps.