OK i think i'm getting the hang of this...
I'm going to run the ISO from an ext3 filesystem. it's located at /isos/whoppix on my (hd0,1) as well as the minirt26.gz and linux26 files. so here's what i've got in my menu.lst file for that entry:

title WHoppix Linux
root (hd0,1)
kernel /isos/whoppix/linux26
initrd /isos/whoppix/minirt26.gz

Is that all I need? i'd like to prevent writing to the HD at all costs - is there something I should be appending to the root line to make it mount the FS read only?