hey that schematic may exist, but there is not much to it.
All you gotta do is jack up the truck, possibly remove the pass front wheel, support it with a jack stand and get under there and look at the frame right near the oil filter.
You will see where the ground cable connects to the frame.
UNbolt that, pull the cable out by the battery,
You may have to cut some conduit to find the path of the + cables, but thats no big deal.
You can do the solder and replace method, but battery cables are a problem on early Explorer's. They get old.
So if you need to extend them your best bet is to kill 2 birds, 1 stone, and replace with longer.
If you can fab a cold air intake with PCV you are fully capable of replacing the cables, no problem!!!