The floppy drive is not necessary to do a sucessfull install of knoppix. I believe that there is a command to create a boot floppy inside knoppix. If you want you can do it at another time other than the install. You do not need a floppy drive to install knoppix unless your computer dosen't support cd booting.
Consider removing your grub loader and use the knoppix-installer program. It uses lilo to boot. I have had no problems dual booting. I looked at the url in your message. Why reinvent the wheel?

Boot Cd.

Enter Cheat codes(I think they should be named necessary codes).

Open a shell and type

Code:
sudo knoppix-installer
set-up partitions

configuration of users and password, choice of knoppix or debian install

start install(15-20 minutes)

get a cup of tea

choose no for boot floppy if you dont need or want one

finish-up

reboot

remove cd before it boots lilo

choose os... 30 seconds..linux default.

johnb