To change the keyboard layout we need to install loadkeys command.
1. Go to packages directory
cd /boot/packages
2. Download kbd package which contains loadkeys comand
wget http://mirrors.slackware.com/slackware/slackware-13.37/slackware/a/kbd-1.15.2-i486-1.txz
3. Install package by rebooting or manually
reboot
or
installpkg kbd-1.15.2-i486-1.txz
4. Load your keyboard map
loadkeys fr # for French keyboard