Dehydration is the biggest battle. IF the pup can be kept hydrated, it's chances are better. Plain pedialyte by mouth, even a few cc's at a time if that's all the pup can hold down. Don't even try with food yet.
If it goes to the bloody diarrhea stage, it's a good bet it won't make it. If your brother, or anyone he knows, happens to have some Tamiflu laying around left over, I believe it helped me to save a litter a few years ago when the new strain CPV 2C (I think that's what it was called) hit town. I had one pup spend nearly a week in the ER and get down to skin and bone but he survived. His littermates (2 of whom were starting to show signs) I immediately started on the Tamiflu, and they turned around almost immediately.
I think the dosage was 10 mg. twice daily for pups NOT showing signs yet, and 20 mg. twice daily for sick ones.
Keep in mind that if the pup is already reeeeeally sick, the Tamiflu probably won't help it, but I would DEFINITELY start the littermate on it ASAP. It works by preventing the virus particle from entering cells - if the body is already saturated with virus, it won't help so much.
Here's a link.
http://www.petcarerx.com/pcrx/HealthGuide/Medications/Medication.aspx?mid=12846
Bear in mind that if money is a factor, Tamiflu is expensive, I think I spent 80 bucks on enough to treat my pups' 5 littermates. Of course that was pretty cheap compared to what we spent to save Arian! That's why I said, call around friends, family, etc and see if anyone has a dose or two laying around. Capsule form, I just poured out the powder and using the good ol' razor blade eyeballed the amount to come as close to 20 mg. as possible.