Out of curiosity, I got the slackware pkgtool.txz package, decompressed it and installed it on slitaz. I also added the /var/log directories that installpkg and pkgtool expect to find. When I used them, I got error messages related to busybox utilities that mimic gnu utilities, but without all the gnu options. It is theoretically possible to install slackware programs like gkrellm, acpitool and lm_sensors on slitaz, but not this way.
Also, busybox may be implicated in making cpufreq-set not work. Acpitool reports that loading frequency governor modules does not make the cpu work under the module, so I assumed this kernel requires cpufreq-set.