Has nothing to do with first person shooters or away3d, your looking for mouse coordinates regardless of mouse position
To break out of flash into browser mouse coordinates, use javascript, ala http://www.frontenddeveloper.net/wiki/index.php?title=BrowserMouse_for_AS3 To break out of browser limits, require the user to click and hold (click and hold the flash/browser in above link) You can find a similar example http://ambiera.com/coppercube/demo.php?demo=walktrough
