I'm trying to install the last version of maatkit in debian Lenny. I couldn't find a repository with the last version, so I got the .deb file. The problem is How to I install this file? man aptitude gave me no clues.
A repository would be the ideal solution. bonus point if you know a repository with php 5.3
You can use dpkg directly. The command dpkg -i packagename is what you probably want.
You could also install and use gdebi-core. With it you can install a .deb package and also get the dependencies if you needed them.
dpkg -i my_deb_file.deb