Newbie,
Can't find my photos of foot straps and boat is in winter storage in VT. Lemme know come Mar/Apr and I'll take a few pics if you want.
The criss cross is easy to make - you need about two 10' lengths of..say..1/4" bungie and four small blocks. In the central region of each bungie, you thread on a block, do a simple end-loop knot. Now put the other one about 3 or 4 feet from the other. You now have two bungies, about 10 ft long, roughly divided into thirds by these two loop-knots with the small blocks on them.
How, simply tie each end of the bungie UNDER the tramp - one end to the front pylon and the other to the back. Same on the other side. Bungie should be under slight tension.
Now, you need small/fine bungie in two pieces. I use small diameter stretchy black shock, nothing special. On each side, you secure it to the FRONT dogbone/trap line, run under the tramp to the opposite side FRONT pully, diagonally back to the BACK pulley and back across to the BACK trap wire on the opposite side to the original front trap line. Tie bungie with slight tension which now pulls the original fore-aft bungie inwards. This helps keep all bungie lines under tension and hidden up under the tramp. Now you do the same to the other trap lines. When your done, the port front trap wire is connected to the starboard aft trap line and visa versa.
I switched to this system 'cause you can trap out right over the stern of a H16 with absolutely no forward pull on your trap line. But hey, whatever floats your boat. If you think the simple system is better than go for it. I sail singlehanded and need to move fore/aft a fair amount and can do this easily with this system. With 2 on the boat, movement is more restricted and perhaps the simple system mentioned by others above will suffice.

Hope this helps

Ron