At some point you may need or want to compile your own Linux kernel from source for Slackware. For example, you may have some hardware that does not work with your current kernel.
This is a well-written, thorough guide on how to compile a Linux kernel from source. If you’re running GRUB rather than LILO you’ll need to change a few entries. As always back-up your data in the event that you hose your system (I’m not recommending that you compile a kernel as there are risks involved).
This guide works for me. The guide is written by Eric Hameleers, a Slackware developer.