Found these on the internet:

I carry a small Rod holder with a number of 6013 and 7018 rod, a piece of welding glass and gloves. I also have two sets of Jumper Cables. I just made up some small 18 inch long battery cables to make the connection cleaner. Connect the batteries in series, 2 minimum, three is best. Use the negative as ground and Positive as the rod holder. My jumper cable clamps do a pretty good job at holding the Rod. With two batteries the small rod burns nicely, the bigger rod was harder to control. The bigger rod burned much better with three batteries. Of course the state of your battereis would make a big difference. Fooling around in the garage I poked a hole in 1/8 x 2 x 2 steel angle, then cut a 6 inch section off with one rod. The only think I would change is to get a real helmet and a light sensing helmet would be best, but they get bulky to carry around. Its more of a juggling act to hold the glass in place while striking an arc. If I have time I'll take a picture of my setup or maybe I'll buy some welding cable, clamps, rod holders and sell some sets to fund my retirement.

I've done quite a bit of trail welding with the jumper cables. It seems when you wheel hard with XJ's something always needs to get welded. What you need is very simple. I carry jumper cables anyway, so I just throw in a rod container, helmet, gloves, small wire brush and slag hammer. The brush, hammer and gloves fit inside the helmet, so it takes little storage room. I carry my auto darkening helmet because I have room for it, and it's so much easier for me to weld with. I carry mostly 6011 rod in 3/32 and 1/8, because most of the time on the trail your welding vertical or upside down, and it's not always real clean, so the 6011 rod works better. I also carry some 6013 rod, but not 7018 because it needs to be flat and there's little flat welding on the trail. I've found that it's easiest to hold the rod with a vise grips, which is in my tool box anyway, and attach the positive end of the jumper cable to the vise grips.....much better than trying to hold the rod with the cable clamp. Like Ray said, two batteries works for 3/32 rod, 1/8 rod takes three batteries. So, jumper cables and vise grips are already there. Throw in the rod container, helmet, gloves (light ones), brush, and slag hammer if you want it, and that's it.

So it apears all you need is:
2 batteries (or a battery from another vehicle in addition to yours)
2 jumper cables (one for welding, one to run the batteries in series)
6011 rod in a container (kept dry)
Welding glass (or helmet if you have the room)
Leather Gloves (or welding gloves if you have them)
Wire Brush
Slag Hammer (optional)

Sounds pretty simple.