You can try if the Slackware packages I have at http://www.slackware.com/~alien/slackbuilds/freenx/
work for you. The packages are 5 months old, so some of the software has has upgrades in the meantime, but they should still install and work for Slackware 10.2.
Now, STX and Gobolinux Desktop do not ring any bells here. You say you want to "view" them on Slackware; are you sure you want the NXServer and not just the NXclient? The nxclient tarball you can download on nomachine.com works fine on Slackware.