ZBrushCentral

Request simple (?) script for resizing brush

I know there are scripts where you press a htokey and drag, but I like the hotkey system of pressing the [ and ] keys lke in paint programs. THere is already a script included in zbrush which resizes the brush in jumps of 10, but that is too much.
What I would like is a dynamic resizing using the [ and ] keys, so that it resizes in jumps of 10, but when the brush gets to 50 or below, it changes to jumps of 5, and when it gets to 10 or below it moves in jumps of 2.
Is this possible?

Failing that, a simple script that always moves in jumps of 2 using the [ and ] keys would be great, and also one that changes the intensity in jumps of 2 using the - and + keys.
I’m sure some of you coders could knock that up in minutes.
Thanks in advance, it would really help me out.