Using Open Directory you can push out a key to stop the automatic Spaces switch when a different application in a different Space steals focus. To do so, first open Workgroup Manager and click on the group in question. Then click on Preferences and then the Details tab. Next, click on the + sign and browse to /System/Library/CoreServices/Dock.app. Next click on Dock and click on the pencil. Here drop down the Often disclosure triangle and click on the New Key button. From here, name the key workspaces-auto-swoosh and set the Type to Boolean and the Value to True.