I wanted everything to look nice so I kept the rubberized molded end from the wire and cut some notches on the housing so when I closed them up, everything would look nice and neat. you don't have to go through all this trouble but it makes it look nice.
I also hot glued the wires a little to the casing so they would not pull out.
After this, you can wire the box up any way you like. I bought the box at a local surplus store and the original wires that were sticking out were pulled back in and cut down so I had room to fish the new wire inside. I tied a not with the new wire inside the box so it could not be accidentally pulled out.
I also had a broken tape measure that I kept around so I took the belt clip part and added it to my battery box with a small nut on the back so it would not come off. I'm a pack rat at times but some things do come in handy and it also helps to reduce all this junk we throw out!