Bit radical, but....

Why not get a cheap MPG? Plugs straight into PC/Mach3, gives you ability to "wind" table, and you can set up buttons to do things like start/stop spindle while you are doing "manual" machining. My own (smaller) CNC mill has pop-out handles for manual operation but as soon as you disable servos you have lost DRO function, and you need to rehome before any CNC operations. I use the MPG a lot for manual positioning, even if I enter a line of gcode to do a controlled cut in place of twiddling the MPG knob at a steady speed. MPG can move table faster than I can wind the table handwheel as well!