Instead of carrying a shoulder bag strap as well as a Black Rapid strap on the shoulder.
I wanted to combine both onto one strap for the Lowepro Classified 140 AW
A quick trip to the hardware store to get a 6mm "carabiner" meant the conversion was complete.
The bag's shoulder strap is now also the sling strap and functions exact the same as the Black Rapid strap, it is worn across the body (ala Black Rapid), with no problems bringing the camera to the eye.
You should be able to do this to any bag strap provided there are no buckles obstructing the path
Using a carabiner, allows you to attach it to the bag strap which is normally a stitched and reinforced closed loop of webbing.
You just need to match the size of the carabiner to the width of your bag strap.
Make sure the diameter of the carabiner is not bigger than your Black Rapid Fastner attachment and also use a carabiner that is designed to be weight bearing.
I re-used an Black Rapid FastenR-2 to connect the carabiner to the camera body.
The buckle on the strap stops the camera from hitting the bag and getting tangled in the strap to bag connectors.
With camera resting on the hip, the bag hangs around towards your back. You could also wear the bag on the hip and the camera over your front pocket.
This is how it hangs on the shoulder, the Lowepro shoulder strap does not move when raising the camera to the eye or returning it to the hip.