When you need to start testing a system booting into user space you need a file system. The NFS root file system is extremely attractive for this and has been used for most ports. The NFS (Network File System) makes transaction requests at the level of files rather than disk blocks. This has the saving grace that errors in the new port cause transactions to get rejected. If you are trying to debug a new port and a SCSI controller driver at the same time you will instead spend much of your time reformatting and reinstalling the disk you are attempting to boot from. Using NFS bounds the possibility for errors and also makes it easier to add and edit files as you attempt to make the machine work.
The initial installs were done with a set of tar files for the m68k known as "watchtower". Watchtower is extremely outdated but is small and it was easy to unpack. Since the goal was getting a shell prompt the age of the binaries was not a serious worry. Watchtower also demonstrates another strength of Linux/m68k. All the ports run the same binaries. Instead of having to cross compile and debug all the binaries for the Macintosh I was unpacking and booting a file system set up for installation on a Commodore Amiga.
With a few modifications to the drivers and several small bugfixes to the kernel code the applications started to run. As most of the code you need to add for a new M68K platform is drivers and setup code once things started to work most applications sprang to life. It took a couple of tweaks to get floating point to always behave itself but once done I was able to boot the machine fully multi-user, but without keyboard, mouse or hard disk support.
It took almost a month before anyone else got the kernel to boot on their own machine. A lot of debugging removed some rather bad assumptions that had 'escaped' the code clean up and gradually other MacLinux 68K machines began to pop into being. This is an extremely important step for any project as it allows other people to contribute effectively. Michael Schmitz wrote the SCSI drivers and much of the keyboard and mouse support. He is now adding IDE. Numerous other people have tested and debugged the code on the many varieties of Macintosh, and even made it work on some.