The only laser grips for the 4046 that I know of are the Crimson Trace LG-359.
These fit all of the S&W metal frame, semi-auto, full size, double-stack, 9mm and .40s&w pistols (5906, 4006, 4046, 5943, etc.)
I don't know if Crimson Trace still makes them.
You might still find a set on the internet.