Full gide is here. Short:
1. Download Notes 8.5.1 for debian platforms and extract the files.
2. sudo apt-get install ia32-libs
3. install getlibs from http://frozenfox.freehostia.com/cappy/
4. issue the following command:
> sudo getlibs -p libavahi-client3 libavahi-common3 libavahi-glib1 libbonoboui2-0 libcroco3 libdbus-1-3 libdbus-glib-1-2 libeel2-2 libgnome2-0 libgnomecanvas2-0 libgnome-keyring0 libgnome-menu2 libgnomeprint2.2-0 libgnomeprintui2.2-0 libgnomeui-0 libgnomevfs2-0 libgsf-1-114 libgsf-1-dev librsvg2-2 librsvg2-common libselinux1 libsepol1 libstartup-notification0 libxkbfile1 gtk2-engines-ubuntulooks gtk2-engines-murrine
5. install the Notes Deb files:
sudo dpkg -i –force-architecture ibm-lotus-notes-8.5.1.i586.deb
6. sudo apt-get install ttf-xfree86-nonfree
7. replace some libaries from:
http://linux-aha.de/wordpress/wp-content/uploads/2009/10/notes_libs_karmic.tgz in /opt/ibm/lotus/notes with the ones from the link above . Make sure they are owned by root and that they are executable. Set the permissons like the ones of the other libraries in /opt/ibm/lotus/notes