ncHoverFocus is a small addon that allows you to easily set your focus by clicking with a modifier on units and unitframes. The mousebutton and modifier are configurable. Every unitframe addon should be supported. This addon has very little memory usage(~7kB) and 0 CPU.
Install and go! The default modifier is alt and the default mousebutton is the leftmousebutton. The slash command is /nchf or /nchoverfocus.
/nchf mod [arg] - Changes the modifier key to arg. Arg must be either "alt", "ctrl" or "shift".
/nchf button [num] - Changes the focus button to button num. For more help type /nchf button help.
/nchf reset - Resets all config to the default.
About the button numbers, every mousebutton has it's own number. The most common ones are these five: