I got it (CHDK for SX150IS). Installed it. It works, but you have to be experimental (like try the flippin Konami code) to get into the ALT menu because there is no "Shortcut" button, like on the SX130. I had to do some random multi-button pushes that are not documented correctly in the README.
Also, I know CHDK is not supposed to be permanent, but is there any chance it can mess up the existing firmware? I might be tripping, but the display looks alot more noisy now, and super vivid colors are all strange and washed out, even with CHDK deleted off my card. I hope I didn't just wreck some system internals, if that's a possible risk with "APLHA".
Is anyone else testing? I hope this is the right thread to have this exchange.