Conky can be installed using SlackBuild scripts, and those script can found from

https://slackbuilds.org/repository/14.2/development/lua/

https://slackbuilds.org/repository/14.2/libraries/tolua++/

https://slackbuilds.org/repository/14.2/libraries/imlib2/

https://slackbuilds.org/repository/14.2/system/conky/

All these four packages must make and install. Also .conkyrc file is needed.

If not wanting to build yourself, I made ready Slackware-14.2-conky.tar packages.