buy a HD video converter model - LK-219413 and run it throgh The VGA input on the 9310,,, The BNC adapors are useless for what you are trying to do. Make sure to keep the LK219413 where you can get at it since it goes into standby mode if it doesn't see a signal for a while and you will have to push the standby button to reactivate it.
BTW don't mount the 9310 upside down or you will kill it quick.. its a Great projector for outdoor shows. it has a 400 watt matal halide lamp and will kick the crap out of most of the newer projectors. Don't let the 2100 lumen specks fool you, By todays standards it would be in the 5000 Lumen range.