1. http://www.slackware.com/~alien/multilib/
2. slackware:multilib

cd /home/share/mirror.nobak/slackware/multilib
lftp -c 'open http://bear.alienbase.nl/mirrors/people/alien/multilib/ ; mirror -c -e 14.2'

This command can be used for syncing your local mirror later.

su -
 
# Upgrade your 64bit gcc and glibc packages & install "compat32-tools":
cd /home/share/mirror.nobak/slackware/multilib/14.2
upgradepkg --reinstall --install-new *.t?z
 
# Install 32-bit compatibility packages
upgradepkg --install-new slackware64-compat32/*-compat32/*.t?z
reboot

Add two lines to the /etc/slackpkg/blacklist file:

[0-9]+alien
[0-9]+compat32

See slackpkg_usage_for_a_multilib_system

Example package: fakeroot

su -
source /etc/profile.d/32dev.sh
export ARCH=i486
cd fakeroot
./fakeroot.SlackBuild
exit; su - # removes /etc/profile.d/32dev.sh
convertpkg-compat32 -i /tmp/fakeroot-1.12.4-i486-1_SBo.tgz
upgradepkg --install-new /tmp/fakeroot-compat32-1.12.4-x86_64-1_SBocompat32.txz

Note: 32dev.sh is part of package compat32-tools