I just checked, and it is not possible to install the Debian unstable (Sid) binary package for LyX without modification, because of a dependency-- libboost-filesystem1.34.1. So the prevu way is the solution, as it will modify the package's dependencies for Ubuntu.
LyX 1.5.5-1 should be synched into Intrepid and it should be officially backported in hardy-backports. If need be, I will open new bug reports.
I just checked, and it is not possible to install the Debian unstable (Sid) binary package for LyX without modification, because of a dependency-- libboost- filesystem1. 34.1. So the prevu way is the solution, as it will modify the package's dependencies for Ubuntu.
LyX 1.5.5-1 should be synched into Intrepid and it should be officially backported in hardy-backports. If need be, I will open new bug reports.