You can do the following:
Code:
su
(enter root password)
kwrite /etc/apt/sources.list
You should see a list of places to download Debian packages from. In Knoppix, these download mirrors are in Germany. You can edit them if you want. I live in the U.S., so I usually change them to U.S. mirrors. Here is what my sources.list looks like:
##Debian Stable
deb ftp://ftp.debian.org/debian woody main contrib non-free
deb http://non-us.debian.org/ woody/non-US main contrib non-free

##Debian TESTING
deb ftp://ftp.debian.org/debian sarge main contrib non-free
deb http://non-us.debian.org/ sarge/non-US main contrib non-free

##Debian UNSTABLE
deb ftp://ftp.debian.org/debian unstable main contrib non-free
deb http://non-us.debian.org/ unstable/non-US main contrib non-free

##Debian security updates
deb ftp://security.debian.org/debian-security sarge/updates main contrib non-free
deb ftp://security.debian.org/debian-security stable/updates main contrib non-free
What I was saying is that you need Debian "unstable" mirrors on the list to get the latest software. New versions of software first go into "unstable", then after some time/bug fixes, they move to "testing". Even though it says "unstable", it doesn't have major problems and many people run completely "unstable" software. Knoppix is a mixture of "testing" "unstable" and custom stuff.

Once you have your sources.list file set up:
Code:
apt-get update
apt-get -t unstable install openoffice.org
There is a howto on this site for using apt and dpkg to install software, you should take a look at it.