I couldnt find the PS.F12 file on in the zip file (see screen shot) Maybe thats the problem?
Correct.
Normally CHDK packages labeled "full" includes also the PS.FI2 (ps.fi2) file. But ATM the SX150 beta port only support loading with a locked card, there's not a PS.FI2 available yet.
I keep getting 'update file error !!!' when i try to boot the firmware from the menu method.
This means: the PS.FI2 file you're trying to load doesn't match your camera, therefore the loader mechanism rejects the file.
I guess you've either renamed the diskboot.bin or you've copied a file from an other CHDK package to your card ?
This won't work...
--> "diskboot.bin" is the 'native' CHDK binary file, loadable with a CHDK-bootable, locked SD card
--> "ps.fi2" is exactly the same binary file, but encoded to be used with the "Firm update" mechanism
Edit: ok i now understand that you can access alt mode by pressing disp while holding the set button down.

... maybe in the next version of the file it will be included.
This port is in an very early state, give the developer some more time to complete the port...
Meanwhile use the "locked card" loading method to test the available beta version(s) and report your results here in the porting thread
