Loading other firmware
 

I see that the firmware is sitting in /lib/firmware. How does the kernel get it? Some forums say, it's through udev, but I don't see anything special in /etc/udev/.

What I really want is to load firmware from a custom directory, so that different versions of the kernel get to use different firmware. Is that possible to do in Slackware?

It's "/lib/udev".
You can see it from the "cat /var/log/packages/udev-*" command.