Here's how to setup the Damn Small Linux Live CD. It is fairly straightforward, but getting some hardware to work can be tricky if you're unfamiliar with Linux. I'll go through a whole HD install sometime later, when I have some more spare time.
First, you'll need the DSL Live CD and a boot floppy. You can find these at http://distro.ibiblio.org/damnsmall/current/
Grab dsl-4.4.10.iso and bootfloppy.img.
The boot floppy is not required if you're using at586, as it can boot directly from the CD, but ct486 is the recommended driver. Alternatively, you can use Smart Boot Manager on a bootable floppy to boot from the CD.
Start MESS with the DSL ISO and boot floppy mounted, with ramsize set to 64m, and use svga_s3 in the first ISA slot. Press DEL during the memory test to go to the BIOS setup, and make sure you enable the floppy drives, any hard disks (not required), and make sure that the boot order is A: then C:. Select Save to CMOS and exit. Now wait, and let the floppy image boot. You will be greeted with the splash screen and the boot: prompt. Here, enter "dsl xsetup" (without quotes) and press enter.
This will make xsetup run before starting X11, so that video mode and some other stuff can be set.
Next, you'll get a message saying something about passing an undefined video mode number. Select any option you wish, except for 'scan'. Or just press Space to continue on.
Now, DSL will start booting. This can take a bit of time, so make a cup of coffee while you wait.
After a little while, xsetup will be run, and gives you an option of which X server to use. Select XVesa.
Select No for USB mouse, and IBM PS/2 mouse wheel. MESS does not support these at this time.
For mouse port, select com1, since MESS only currently supports serial mice.
For number of mouse buttons, select 2 mouse buttons.
For resolution and bit depth, it's up to you, but 800x600 and 16bit work okay with the 9FX Vision 330 video card (svga_s3).
Select No to choosing your own DPI.
For keyboard mapping, it's your choice, but the default US works fine.
After all that, you should be greeting with the standard X11 cross-hatch pattern, and eventually a usable desktop like this:
Now, some hardware you may be using don't have their drivers installed yet, as MESS only properly supports ISA (not ISAPNP, VLB, and minimal PCI on at586), so you have to load these manually.
Networking (requires a build compiled with USE_NETWORK=1):
IRQ3 seems to conflict with something in Linux, even though it doesn't list anything as using it. This means the 3c503 network card is not really usable. But the NE1000/2000 is, with their IRQ set to IRQ5 (you can set this in MESS' System Configuration menu).
Open a terminal (either the Term button on the taskbar, or DSL->XShells->... menu). At the prompt, type (without quotes) "sudo modprobe ne io=0x300 irq=5" and press enter. Run dmesg at the prompt to make sure the driver is loaded. Now, load the DSL Control Panel, and click Netcardconfig.
If your local network uses DHCP, set DHCP Broadcast to yes, click Apply then Exit. Otherwise, fill in IP Address, Broadcast, Gateway, and Name Servers. IP address will be the IP for the emulated system, and Gateway will be the IP of the TUN/TAP device MESS will use (I guess there's something similar for Win32 and OS X users using PCAP), and click Apply then Exit. Now you should be able to browse the net. Firefox is included, and usable, if you want something that is better than Dillo, just be prepared to wait a fair while for it to load.
Just loading the driver should be enough. Open a terminal, and enter:
sudo modprobe gus io=0x320 irq=7 (Gravis Ultrasound - IRQ and DMA is software configurable, so set it to an IRQ/DMA channel not in use)
sudo modprobe sb io=0x220 (Sound Blaster)
You can use floppies, HDs and CDs, by mounting them via the Mount tool (click the Mount button on the taskbar). Click the top button to cycle though mountable devices, and the bottom button to mount or unmount the media. Contents are viewable in the various folders in the /mnt folder. For example: mount the cdrom, and at a terminal prompt display a listing with "ls /mnt/cdrom/" Media can be any formatted any way that Linux supports (ext2, FAT, FAT32, ISO9660 [CDs], among others).
If you have formatted hard disks mounted, you can use them to save settings to. The HDs can be formatted in ext2/ext3 or FAT/FAT32 or anything that Linux 2.4 supports. From the DSL Control Panel, click Backup/Restore, enter the device name (for the first partition on the first IDE hard disk, use /dev/hda1), and click Backup. Now you can shutdown and settings will be saved to the HD.