this is my /etc/apt/sources.list.d/hildon-application-manager.list, i got it installed without problems. i think the relevant row is the first one

deb http://catalogue.tableteer.nokia.com/certified/ diablo user
deb http://catalogue.tableteer.nokia.com/non-certified/ diablo user
deb http://catalogue.tableteer.nokia.com/updates/diablo-2/ ./
deb http://repository.maemo.org/extras/ diablo free non-free
deb http://repository.maemo.org/ diablo/tools free