hmm if I remember correctly, yast is only SUSE's configuration and administration front end. Slackware's native package manager is pkgtool, a simple system (written in bash) that uses plain gziped tarballs with specific directory/file structure as packages, to manage it's software database. Of course RPM packages could also be used in slackware but it is not adviseable. Not because of the RPM system itself (which technically is very similar to slackware's in the way it works), but because of the fact that most RPM packages are built with redhat distributions in mind, which have some differences from slackware. Differences in things such as default directories, initialization scripts system, users, groups and permissions, facilities like udev and sysconfig and other such.
Depending on the particular software and what facilities the package is compiled to utilize, an rpm package may or may not work well or at all on slackware. Unwanted effects could vary from the use of non-standard installation directories, that could result in organization or dependency issues, to inconveniences with the control scripts or even the total inability to execute properly.
So it is sugested if you use Slackware to avoid rpm packages whenever possible.
