After installing 64-bit version of Slackware Linux, we have ready distribution for running 64 bit applications (obvious!). But there may be some problems with 32-bit software. Installing multilib package can solve this problem. This step should be one of the first operation after install Slackware64.
Multilib installation is very easy. First of all, you should download appropriate files, using command:
lftp -c 'open http://slackware.com/~alien/multilib/ ; mirror 14.2'
As you see, in the end of this line is version of Slackware – if you have different number – just change it.
Subsequently, enter the folder you have just downloaded and type in terminal with root privileges type the following commands:
upgradepkg --reinstall --install-new *.t?z upgradepkg --install-new slackware64-compat32/*-compat32/*.t?z
This is it! Now you can run 32-bit application without problems in Slackware64.
P.S. More information about multilib you can find here