Ok, what I have done so far - and please keep in mind that I am a complete newb at this whole electric and soldering thing.
I had a broken wall charger, so I took that apart and salvaged the part where the battery connects. I took that part apart and found that the original problem was in there, but the board was too far gone at this point to repair the whole charger. At this point, I repaired the problem inside the little housing where the battery is supposed to connect to the charger, then connected this little housing to a 3AAA battery holder with some PVC electrical tape. It worked - it charged batteries, but I had to undo half my work every time I needed to change the AAA batteries. Next, I wired that same little housing to a USB male connector. After much frustration, I found that I had the polarity reversed on my wiring, fixed that problem, then my ugly USB charger worked. I was worried I might harm my computer using this thing, so I scrapped the idea.
Next project. One of my batteries died and I was dying to try this Magnum Mod. I played hell trying to get the fitting off the end of the battery - I think Madog must have a grip of steel. I took apart the little connector housing from that first project and salvaged the little nut that was serving as the negative terminal. I screwed this nut onto my dead battery, then used pliers to grip that nut and wiggle the connector free - the added leverage helped loads. I did manage to complete the Magnum Mod on one of them cheap little LED lights from the Dollar Tree, but my soldering skills are horrid and I have now broken one leg off my switch. I replaced the switch, but now have the same problem with another switch. I can't seem to get my little wire soldered on to the leg of the switch without making the switch leg very brittle. My plan is to mod my mini Maglite, but I don't want to sacrifice my Maglite until I can make it worthwhile.