The mode map for that camera is not correct, so raw exceptions wont work.
You can help us fix this:
In the CHDK menu, got to miscellaneous stuff -> debug parameters
Set "Debug data display" to "props"
Set "PropCase/ParamsData page" to 0
Leave the menu. You should now see the propcase display, which is a window with some lines like
Switch to record mode.
The value after 0: should change every time you change the shooting mode.
Now select each possible shooting mode, and write down the mode and the value after 0: in the propcase display.
Note that this should include not just the modes available in the dial, but also the various sub-modes you can select in scn mode etc.
I also am not able to get it to switch between RAW and JPEG by using the ALT+FUNCTION shortcut.
If I've read things correctly, the raw shortcut should be the display button.