I cleared out a 20GB partition... and formatted it as an ext3 partition before I ran the new installer, 0wn. That's a zero.
Then I read some of the scripts. 0wn is actually /usr/sbin/0wn and it has some support scripts in /usr/share/0wn.

I chose the middle option which was a Knoppix on hard disk option... likely to preserve as much Knoppix as possible.

Since I had 970MB swap space... I decided to edit 0wn-common to reduce it to SWAP_NEEDED=$((1000*974))
111 # this is no real necessity, just policy
112 SWAP_NEEDED=$((1000*1024))

In reading it, it seemed as though it might allow me an option to append my already existing menu.lst, but I didn't get that option.
So rather than let it mess with my mbr I chose the other way. For it not to modify anything on my boot drive. It left a menu.lst in the newly installed knoppix partition... in /boot/grub/menu.lst. So I copied the Knoppix item to mine. I did notice it had lang=de in the menu item and so I changed that. (When I booted up... kde was in Gerrman as well!)

This is great.

If you haven't tried out the 0wn installer... give that a shot.
Alternatively, you can run from the iso file you downloaded... using grub4dos, and Gilles Van Ryumbeke's enhanced minirt.gz.
http://www.knoppix.net/forum/viewtopic.php?t=11796 has more details about that method. Googling minirt_531.gz should get you the related pages quicker than a search here.
Grub4dos allows you to dualboot without messing with any modifications to any vital drive areas, like the mbr. You simply tell windows to load it, which it does... and off you go into linux land.