OMG!! It can't be this easy.
After reading all that info, I did two simple steps. I ran the rpm2txz command (with all those options) on the 2 rpm pkgs and then installed the txz pkgs (lpr 1st). Voilą! When I went back to the cups webpage, there was my printer. I printed the cups webpage from my browser and the printer worked flawlessly. I LOVE Slackware. I love Brother printers. Allend, ....well, I like you a whole bunch. Thank you for the that excellent link. Kiki, I thank you, too, even if I don't really speak French. I've always been a bit wary of that rpm2foo command, suspicious it didn't really perform as advertised. Silly me. Now I know better.
Again, thank you all.