Since I’m not sure exactly how you want the objects scaled down, one of these should work for you:
To scale them all down together, press ‘A’ to select all, then scale down with S as usual. If it doesn’t do what you wanted, you should scale them all in manually, or ask someone to write a script to scale all the objects to a certain size on thier individual axis. Either that, or, if you want them their normal size, as in the size you modelled them at, select them (each seperately) and press ‘Alt-S’ to clear their size, scaling them to normal. A person could also write a script for doing this, but I figure doing it manually would be faster than waiting for it, and then running it.
Hold on Tight,