This was much easier than I expected. Note that I'm running Slackware 13.1 32-bit.
Step 1: Install the latest NVidia driver (256.44 in my case). You can't use the SlackBuild from slackbuilds.org. The latest NVidia packages are quite different from 195.*. I uninstalled the existing driver (that I had earlier installed from slackbuilds.org), downloaded the latest NVidia driver, and installed it according to the instructions.
Step 2: Install the CUDA toolkit for Fedora 12. This amounted to downloading the file and running it. I accepted all the defaults.
Step 3: Install the CUDA SDK. Again, I downloaded the file, ran it, and accepted the defaults.
Step 4: Change the paths according to the CUDA instructions.
Done! This was so much easier than Ubuntu, Mint, Debian, and others. I didn't expect it to work by just downloading a few files and running them. I'm certainly not complaining. I ran make for the examples, they all compiled and ran perfectly.