I haven't worked with Slackware in awhile so I don't know if you will have other issues, but this is what I do on Fedora.
mkdir ~/build # A directory where your build will be built.
make O=/home/name/build/kernel mrproper # Replace name with your username. This will clean up any .o from an old build
copy your config file to .config in your source directory
make O=/home/name/build/kernel oldconfig # This parses your old config and updates it with new options.
make O=/home/name/build/kernel menuconfig # Make your 2 tweaks
rm .config in the source directory # I think your build will sense this and not allow you to build if you don't
make O=/home/name/build/kernel # This is the build. It takes awhile to execute
sudo make O=/home/name/build/kernel modules_install install # This copies your bzImage to the /boot directory
# Sets up some symbolic links and updates the grub.cfg
Reboot and test.. If you have other problems, please reply to this thread.
- Raj Upadhyaya