I just want to thank everyone for all the helpful advice you gave me. When my parents got home, they were able to fix him up - my dad has decades of experience in treating cuts and wounds such as this in animals, and my mom also has an extensive background in caring for reptiles. So between the two of them, St. George has got it covered.
We moved him into a sterile 7 gal. tank with newspaper as substrate. He has a water bowl, two hides, a food bowl, and a basking spot in there. We've cleaned out his cut and right now he is basking.
As it is a small and temporary tank, we've been using a 5.5" reflector dome with a 40 watt bulb for lighting (we only have 25, 40, 75, and 100 watt bulbs, and anything over 60 watts in the 5.5" dome is a fire hazard). We also have an 8.5" reflector dome that can take 100 watt bulbs. Temps there are 85 on the basking side and 76 on the cooler side. In the big tank, we use a 100 watt "Repti Basking Spot Lamp" we got at the pet store for basking (which we keep in, and a 7.0 UVB fluorescent light. Temps in there are usually about 108 in the basking side and 84 in the cooler side. So should I use the 75 watt with the 8.5 in reflector dome for the small tank or leave it at the 40 watt with the 5.5 in dome? I don't want him to get too cold, but at the same time just using the same arrangements as in the big tank would bake him.