a) Grab usbboot.img from the official ftp/http mirror.

b) Use dd command to write usbboot.img to a usb pen drive.

Examples

To download Slackware Linux version 13.13 using the wget command as follows:
$ cd /tmp
$ wget http://slackware.osuosl.org/slackware-14.1/usb-and-pxe-installers/usbboot.img

Tip: To download 64 bit version, try:
wget http://slackware.osuosl.org/slackware64-14.1/usb-and-pxe-installers/usbboot.img

To create a bootable usb stick, enter:
# cd /tmp
# dd if=usbboot.img of=/dev/sdc bs=512
Where,

1. usbboot.img – It is a 30MB small USB boot image that you can use to boot into the Slackware setup program.
2. /dev/sdc – USB stick

BIOS Boot Options

Your computer BIOS must support booting from USB HDD.

• Start your computer.
• Press [DEL] or [F2] to enter into BIOS setup ( this step is dependent on the type of computer you have, see your computer manual for more info).
• Make sure boot option is set to USB Hard disk.
• Plug the USB stick into your computers USB slot
• Boot the system up.

The Slackware Linux installer will start. Log in as root. Use fdisk or cfdisk command to create partitions:
# cfdisk /dev/sda
OR
# fdisk /dev/sda
To start the install type setup command:
# setup
You can now install packages from a CDROM, hard disk or network locations.

References:

• Slackware Linux project.