I used to maintain several NW 3.12 servers, last one was put down about 3 years ago. It was a Compaq server with hot-swap drives. The "up" time when I shut it down was over five years. A real stable OS. The system was replaced with a MS Server in about 2001, but the accountant needed access to a few programs that were custom written for a Novell network, so the server was left on line and only a few people had the Netware client installed to access it.
Netware 3.12 installs on a small PC DOS partition and loads the OS from a file. The OS loads to a command prompt and runs scripts to load drivers for the hard drive controller, mounts the SYS volume, and loads drivers for the LAN card. The console has a small set of commands to mount drives and load modules, but usually you can't do more than that (3rd party vendors added backup programs, voice mail systems, and others that would install on the server and run on the console). Users would access the server over the LAN by mapping volumes.
It's been about 15 years sense I last installed Netware from scratch, so I don't exactly recall all the steps. I know it came on about a dozen diskettes (later versions on a CD), or you could copy all the files into a folder on a DOS drive and run setup from there. If you are running on an older system with an ISA or IDE drive it should already have the drivers you need. You will need to to locate Netware drivers for the LAN board.
You manually create a small DOS partition for the boot files, and the install creates a netware partition for the SYS volume & VOL1, VOL2... Just boot to the DOS partition and run the install on the floppy or CD, it will copy files and create the loader scripts.
I have a set of original books and software for Netware 3.12 (and other versions), I can put them on eBay if anyone is interested...