Did you mean you tried to install or did you try boot from a DOS disk?
I think any "boot" disk (whether DOS or windows) should be able to fire up the computer enough to get you to dos prompt where you could then run
a:fdisk
and clean out your partitions and reformat.
If you have a set of DOS install disks, disk one should be bootable. If not, try here:
http://dos.li5.org/