BT is a slackware based security distro.
Ah, okay. Perhaps I need to get out more often.
The startkde script cannot be used separately but must be run from within the startx script.
You can manually select the X environment from within KDM, but KDM is invoked from within run level 4 and not run run level 3. In Slackware the run level 3 solution is to run xwmconfig.
If you want the flexibility of running either run level 3 or 4 at boot time, without fiddling with inittab all the time, then perhaps the following will help:
Configuring Slackware for a GUI and a Command Line Startup