It's certainly convenient to be able to do stuff like this right in the camera, but implementing something like this in CHDK would be an enormous amount of work if it's possible at all. I wouldn't reject it if someone else found a way to implement it, but it's not something I'd spend hundreds or thousands of hours into trying to do.
CHDK is subject to a lot of limitations because it is hacked into a completely undocumented system.
I do a lot of Android Mods flashing (CyanogenMod particularly on most) on several of my and my family, friends and relatives cell phones (since I enjoy doing it) and I was hoping that one day perhaps even the camera manufacturers will unite to unify the OS of the camera (like Android did with several manufacturers offering Android as their OS), and releasing the OS source code for their particular Camera, making it easy to port, hack, mod and add functionality to it.
Perhaps then just like android has several famous mods, like CyanogenMod, SlimROM, etc., even the camera's might have something similar, despite being vastly diverse in their hardware configurations! The cellphone industry saw wisdom in it, perhaps one day the camera industry would too? Those who don't will perish like Nokia, despite being on top of their game!
Until then, Post Processing is the only way!
Thanks for your reply though, I appreciate it.