The printer driver packages I downloaded from Canon for my Canon Pixma mp190 multifunction which have worked fine since Knoppix 6.0.1 -see post below
no longer work in Knoppix 7.0 because it now uses the package libcups2 instead of libcupsys2. After some googling I found this post that seemed to offer a DIY solution
This post gives the general idea of what to do.
But in fact it doesn't work on debian/knoppix 7.0 because there is no <deb> command available and archive-manager/file-roller will only open an archive read only [even when run as root] - but what does work is to extract cnijfilter-common####.deb with the command
file-roller --extract-to=./cnijfilter-common cnijfilter-common_3.00-1_i386.deb
[answering yes to the question of whether to create the folder as it does not yet exist]
then go into created folder <cnijfilter-common> and open the file /Debian/control with gedit [as root] and change the entry under line 'requires' from
libcupsys2 to libcups2 - [inserting in the approprate version details for your libcups2 package]
save the changes and then put the .deb package back together again with
dpkg-deb --build cnijfilter-mp190 cnijfilter-mp190.deb
giving it a new name - [which doesn't have to obey all the complex debian package/version nameing rules if you are only doing it for your own immediate use]
then install your new package
dpkg -i cnijfilter-common.deb
and repeat the whole process with the cnijfilter-mp190#####.deb package and install that too
then go to preferences | printer configuration and modify the settings again to change the driver to the one you've just installed
The scangear-common####.deb and scangear-mp190####.deb packages will install fine just as they are, without playing around with them [on my ageing Compaq desktop, anyway].
I doubt if such a simple fix will work in many cases of dependency conflict but it does work in this case. I hope it will help other people too.
Best wishes, John