Too much work wrapping your (message). For years I used what I called my double slash whisper. But now I made it into an alias and enabled the second editbox and use it to notice whisper.

on *:INPUT:#:if $1 = // && !$ctrlenter && !$inpaste { haltdef | notice $$snicks $$2- }

Note that you best haltdef before you notice so your private convo dont go to channel if you have no $$snicks.