Short answer: I don't think you can do that.

Long answer:
On the Mac, each program has a unique name ("World of Warcraft" for example). Even though you created 4 copies of the application, that name will be the same for each one. The window location, however, is stored in your user directory (in the Library/Preferences/com.blizzard.World\ of\ Warcraft.prefs file to be exact). If you carefully look inside that file you will see an entry for WindowBounds. Because all 4 copies share the same prefs file then they will all show up at the same place and with the same size. It looks like the prefs are written out when the application closes so the last one closed is the starting location for all four.

Short rant on my part
On top of that, WoW doesn't accept any AppleScript commands so you can't tell a window to change its bounds. To make matters worse, even if WoW did accept AppleScript tells how would you identify which Application "World of Warcraft" is which?