Thanks for your optimisms.
Update: I can indeed "boot" MkLinux on my 520c with a little help from Wish-I-Were and ResEdit, now.
I simply followed the steps given on MacFixIt (and possibly here) for installing MacOS 8.5 on the powerbook, and downloaded the latest Mach Kernel (GENERIC8a4). I am getting closer, and with a little help from Dave Gatwood at MkLinux.org, I will get it to run.
Email me if you need details about my setup.