kbbrightness utility from EZ2S. I also converted kbledson and kbledsoff to similar scripts instead of full executables, so the jffs disk space useage remains about the same.
Of course now that I've got the desired speed, I need still to convert the demo into a reasonable set of working dialogs. So far I've just added a little bit of code to manipulate a highlighted selection bar with the arrow keys, and then launch the currently selected option with the enter button. I find that handy because even with the keyboard lit up like a Christmas tree it's still hard to find the number buttons, as they're printed in tiny red letters that don't light up. If anyone wants to play, here's the work in progress on the scripts pictured above. Some parts still require the iz2s busybox, so be careful with these scripts if you haven't loaded that on your jffs.
Turns out stty is crucial to the arrow key parsing and it's not available in the base system, only in the iz2s busybox which I currently have upxed on the jffs of my zipit. That makes it way too slow to capture the multi-character arrow (and function) key sequences reliably. I can make it better by only calling stty once, but it's still not an optimal solution, especially since the base jffs has no stty command. I think I may have to try building a stripped down standalone version of stty...