i dont have any links, but i can give you an idea.
you can use a 10 gallon tank or larger if you have any larger tanks laying around. a 30 gal long will be fine for tangs (i think).
filtration. you can use a hang on tank filter such as the
aqua clear and use the sponge that is made for the filter. you could either cycle the tank the old fashion way, or leave several sponge filters in your sump for a few weeks and use them in the quaranteen tank. after you are done with the sponge filters, or use a medication that kills the biological filter, just throw them away (the sponges dont cost that much).
the quaranteen tank is used to treat your new fish or established fish in a controlled environment. most medications are not safe for inverts and must be administered in a seperate aquarium. hmmm, actualy, the "hospital tank" is used to treat the fish, while the "quaranteen tank" is used for observation and they both can be the same tank!
a simple 10 gal tank, no substrate, some simple decorations such as PVC elbows or fake plants, and some form of biological filter (i use the aquaclear), and a heater. lighting is optional. i would also recomend you have the medications needed on hand at all times or at least live close to a fish store that does.
im sure i have missed a detail somewhere (i have a little sister bugging me!), but you should get some links and other peoples advise as well.