taken from the site 4 u mi friend
How to run SLAX Linux from USB FlashDisk
Boot SLAX CD and plug your USB FlashDisk in. Change directory to /boot (or wherever your CDrom is) and start:
./create_bootdisk.sh . /dev/sda1 /dev/sda SLAX
This command will create a directory called SLAX on your flashdrive and it will copy all necessary data to it. The first argument (the dot ".") means that you wish to create a bootdisk from the current directory. Second parameter /dev/sda1 is your FlashDisk's first primary partition and the third parameter /dev/sda is the master boot record of your flashdrive.
You can also install SLAX to your hard disk this way - just replace /dev/sda1 by /dev/hda1 and /dev/sda by /dev/hda. Or use the naming scheme from devfs - /dev/discs/disc0/part1 and /dev/discs/disc0/disc. Note that create_bootdisk.sh script will overwrite your MBR so you won't be able to boot any other existing OS from your USB FlashDisk (or harddisk).