This is an old revision of the document!
Getting Slackware
The official way to do this is, of course, to get it from slackware.com.
Personally, I have getslack, a bash script based on (more accurately, a trimmed-down version of) the excellent (he termed it infamous) mirror-slackware-current.sh by Alien Bob. When going down this path, the next step would be to prepare the installation media.
Slackware Installer ISO Image
Slackware Installer ISO Image
I no longer need an ISO image (refer to USB installer below). But, I have slack2iso script (also based on Alien Bob's script) can help in creating one using the tree downloaded by getslack.
Slackware USB Installer
Slackware USB Installer
Alien Bob has provided a script to make/setup/configure a USB-based Slackware installation media. I wanted to do something simpler using the existing files in the Slackware tree that I mirrored using getslack (mentioned above). So, here is how I got that working.
Create a FAT32 partition
Use syslinux to provide bootloader
Copy boot facilities from Slackware tree to the media
copy a kernel from slackware tree to /linux/boot (I used huge.s)
copy initrd.img and message.txt to /linux/boot
copy isolinux.cfg to /linux/boot/syslinux as syslinux.cfg
edit syslinux.cfg accordingly (initrd, kernel params, etc.)
Copy slackware<64> in the Slackware tree (I used a shorter folder name like slack on the USB)
And… we're done! Now we have a simple Slackware USB Installer and install it on every computer we can get our hands on! 
