In order to build slacktrack:

 # ./slacktrack.SlackBuild -i

This will compile installwatch and turn all the relevant
bits included within this source tar ball into a Slackware package
and will then install it.

The resulting package will reside in /tmp

You may wish to adjust the ARCH variable to match your
architecture though - eg i386,sparc,alpha,arm.

You can do this at the command line by doing 
 # ARCH=sparc ./slacktrack.SlackBuild -i