try xnview_1.68-2_i386.deb available from http://xnview.asos-clan.de/. )I found this by goggling for xnview then search within result for .deb). You can download the package then if you click on it kpackage should install it ok provided there are no outside dependency programs which you do not have. If there are any you will have to install them first.
To make apt-get (or kpackage) automatically take care of dependencies you would have to add http://xnview.asos-clan.de/ to your sources list.