A useful command that can be used in conjunction with pkgtool is rpm2tgz, which converts a pre-built package for Red Hat Linux into a slackpkg (ie, a .tgz file) that can then be installed via pkgtool. This is similar to finding a pre-built .tgz on any given software's download page, except that rpm files are ubiquitous to Linux package formats and the liklihood of finding a .rpm file often exceeds the likelihood of happening across a Slackware package.

Once you've downloaded the .rpm file, use rpm2tgz to convert it:

  rpm2tgz foobar-x.x.xx.rpm

The result is a .tgz file, so after the conversion is finished the original .rpm can be discarded and pkgtool can be used to install the .tgz file. You will need to ensure that the computer contains the dependency code for the application to function; this means that you might need to install other software before installing the application you really want to install. For instance, the Red Hat documenation tool publican offers an .rpm, but in order to install it there are about twenty perl modules that must be installed first, which must be done manually.