Changing mouse size

This is probably a small engine tweak, but looking over the mouse code, I couldn't see a good place to tweak it. I'm looking to resize the area 'checked' when the mouse is clicked on. Not move it, as hotspot seems to do, but better simulate 'the player sees their hand as the mouse, what it touches, they can click and pick up' instead of 'there's a specific click point'. Any ideas?