changing brush cursor to behave like the eraser?

Can anyone tell me if it’s an easy thing to make the brush cursor behave the same way as the eraser? (display a circle that changes size). The brush icon is very distracting, and i think it’s beginning to screw with my head–it’s weird enough for me trying to draw with an icon cursor at all, and a downward-pointing cursor seems to be messing with my hand-eye coordination. Disabling the cursor entirely is not an option…that shows a fat opaque cross which interferes with drawing and doesn’t show the brush size. Plus it overrides some of the other cursors (why only some?) for which the cursor icons are actually useful.

I have a little experience with scripting, so the concept of programming isn’t completely foreign to me, but i don’t really know anything about C++. But if it’s not too difficult, i would be very happy if someone let me know how i could accomplish this.