I used a rope ladder as my "base" hanging it from both the top and bottom on the ceiling. I got this ladder at a pet store for cheap because they get one everytime they buy a bulk order of toys. It is a toy-display ladder so quite large and has eyelets built in to display the toys... or hang toys from when you buy it from the pet store!
I screwed a piece of 2x2 into the ceiling so that instead of poking a hole in the ceiling for every toy hook I wanted, I just needed to poke two holes. From that piece of 2x2, I hung one going parallel to it as seen on the third photo towards the right side. From these 2x2s, I took eyelet screws and screwed them into the piece of wood.
I took branches to "support" the ladder as it was a bit flimsy.... as you can see, it still is. But hey, who ever said that tree branches never move?!?
In the second photo, you can see the boing hangs from the ceiling gym and crosses into the PVC gym for total access.