it will not overwrite anything, but it will copy a KNOPPIX directory and 700mb to the fat32 partitioned drive.
the problem arises when you will want to save your home or config, knoppix will make the whole partition read only, so the home/config cannot be saved.
I got around this by booting to a cd, and partitioning using sudo qtparted, then creating a second fat32 partiton 1 gig in size for the copied img, the config and all my data could be saved on the rest of the drive.

Code:
knoppix fromhd=/dev/sda2 home=/dev/sda1