What I did with mine was:

qemu -m 512 -cdrom slitaz-cooking.iso

Of course, you may want to change the memory, and Slitaz booting from the ISO will not be able to save anything.

Yeah, that's the thing. I want it to be the same as booting from the USB stick normally. I really just need to know what options the kernel looks for so that I can point QEMU to the right files, particularly troublesome are the home directories and the root file system.

You can try :

qemu -m 384 -kernel bzImage -initrd rootfs.gz -hda /dev/null


i have create a qemu img , and install slitaz cooking iso to the qemu img,
boot to openbox ok,

1 check #lsmod output
(0 module)

2 no eth0 device

@guru
qemu default is to emulate a realtek 8139c network card in user mode, wich seems not supported by slitaz cooking.
by lanching qemu with the options -net nic,model=ne2k_pci -net user (or some else qemu supported network card) you change the emulated network card and you can use eth0.

@guitarMan666
i'm using a standard liveusb install with a little (ugly) hack to use it keeping my home both in liveusb and emulated modes.
to boot in qemu i'm using the commandline posted by bellard but using as hda a file called home.img wich is created with qemu-img and formatted as ext3.
to mount the file in slitaz you need to change the busybox mount because it doesn't support

 -o loop,offset=32256

, wich is required to mount the file.
i've downloaded the debian lenny mount and libselinux (wich is required from mount), converted in tazpkg format with

tazpkg convert

and installed.
after that i've changed, in the rootfs of slitaz, /etc/init.d/local.sh like that:

#!/bin/sh
# /etc/init.d/local.sh - Local startup commands.
#
# All commands here will be executed at boot time.
#
. /etc/init.d/rc.functions

echo "Starting local startup commands... "

echo "cheking if booting from a real system or from qemu"

if cat /proc/ide/hd*/model | grep -q "QEMU" 
	then
		mount -t ext3 /dev/disk/by-uuid/12345678-1234-1234-1234-123456781234 /home
	else
		mkdir /mnt/chiaveusb
		sleep 5
		mount -t vfat /dev/disk/by-uuid/1234-5678 /mnt/chiaveusb
		sleep 5
		mount -t ext3 -o loop,offset=32256 /mnt/chiaveusb/home.img /home
fi

where 1234-5678 is the uuid of the vfat filesystem on the usbkey and 12345678-1234-1234-1234-123456781234 is the uuid of the ext3 filesystem in home.img.
This way i can have my ext3 home booting in qemu under linux and windows and as liveusb too. Under linux you can mount home.img with the -o loop,offset=32256 to copy there the file you need. Before to mount home.img as /home for the first time mount it somewhere else and copy all required files in it.
If you have found a better solution let me know ;)