Fantastic, thanks for that.I had to go get the camera out because I couldn't remember how I did it lol.
Anyway, Menu/Set > Custom (the wrench with the "C") Operation > Fn Button Set > Setting Rec Mode
This brings up the little outline of the camera with all the FN buttons highlighted.
I put mine on FN5.
So: Fn5 > Menu/Set > Page 2 of 19 "AF-ON: Near Shift"
The thing that I found confusing, and still do, is that when I hit the assigned Fn button, it focuses without any indication that Near Shift is engaged. All I have to go on is the fact that it refused to focus on the intended subject several times until I hit the button, at which point it changed immediately.
Also, if I remember correctly, this particular function can only be assigned to a physical button, not one of the Fn "buttons" on the touchscreen. I noticed that when you go to assign functions, there are 19 pages available on the physical buttons and 17 pages on the touchscreen buttons.