I can see a problem in your screenshot of SDMInst. Your card has two partitions. You can see from the SDMInst log that that the CHDK directory was copied to the 'acid108' FAT32 partition whereas I presume the DISKBOOT.BIN and PS.FI2 files were copied to the small FAT16 'CANON_DC' partition.
I think you need to reformat the card as one partition. If the camera won't do this, you may need to use the Mac's DISKUTILITY to get rid of the two partitions, then use the camera to format the card as one FAT32 partition, then use SDMInst to mak it bootable.
As a check, when you put the card in the computer's card reader, if there are two partitions you'll see them both appear separately on the desktop.
PS what dbldash suggests will NOT cure your problem - the CHDK directory IS on the card already, it's just in the other partition.