There is GRUB in A series of Slackware-14.1. If you want to install GRUB immediately after install (and before restarting), below is a simple method that assumes you use traditional BIOS and MBR partitioning (if you plan to use GPT instead of MBR partitioning, refer to Grub 2 with GPT and a BIOS motherboard instead):
After the message: “Installation of Slackware Linux is complete.”
chroot in:
# chroot /mnt
Then install GRUB:
# grub-install /dev/sda # grub-mkconfig -o /boot/grub/grub.cfg
# exit # reboot
Enjoy!
P.S. Make sure to run:
# grub-mkconfig -o /boot/grub/grub.cfg
After every kernel upgrade.