I don't even know if this is possible....but I was looking at a vacuum attachment at modularhose.com (
http://modularhose.com/ll25.htm). They only come in the 2.5" hose size, so not sure how feasible it would be! It just struck me as a way to perhaps diffuse some of the flow that usually seems rather direct and focused coming out of a regular loc line fitting.
Edit: nevermind, the link doesn't work. Just go to
www.modularhose.com and select the 2.5" ID System in the menu bar at the top.