Install Slackware Using A USB Flash Drive
Installing Slackware using a USB flash drive is very easy.
Slackware includes a usbboot.img in the usb-and-pxe-installers directory of the official installation media, along with AlienBOB's usbimg2disk.sh in case the above image doesnt work for you out of the box.
This document will demonstrate yet another way of doing this, which from my experience is easier and often more convenient than all of the above. This document will describe how to create a Hybrid Slackware ISO with Isohybrid.
Syslinux >=3.72 is required
Additionally you should either have:
a) official Slackware installation media, preferably the DVD ISO one, available on any Slackware mirror.
or b) a local copy of the Slackware tree. That may be the tree of a stable release, or even one the tree of the -current Slackware development cycle.
If you choose to go with b) you should be able to create your own ISO images using a script such as:
Pat's DVD script
Pat's split to 3 CDs script
AlienBOB's mirror-slackware-current script
or even a custom one of your own.
At this point you should have a Slackware ISO lying on your hard disk.
Make it hybrid:
Copy the ISO to the USB flash drive
Now all that is left to do is copy the ISO to the USB flash drive.
That can be done using the dd command as the root user, that will overwrite all the files currently present on the USB drive.
dd if=slackware-13.1-install-dvd.iso of=/dev/sdX
PS. dd expects the name of the device, not the partition, so you should should eg. /dev/sdb and not /dev/sdb1.