EQ also disables Alt-Tab support, so you need to get around that. This was also cause for windowed mode being banned from the game until last year. You do it by downloading Microsoft's Application Compatibility Toolkit. Run the toolkit and find the EverQuest application in the apps list. You'll see that it says IgnoreAltTab. Right-click on the EQ application entry and select Disable Entry. Save and exit.
This will allow you to switch between EQ and anything else. So I launch EQ on all three computers. Once I log into the accounts, I can start loading the second one by Alt-Tabbing out to the desktop.
This was quoted from an article that can be found
here