To install alien, become root and type "make install".

To use alien, you will need several other programs. Alien is a perl program,
and requires perl version 5 or greater. You must also have the Getopt::Long
perl module installed on your system, I believe this is a standard part of
perl.

To convert packages to rpms, you need the rpm package manager; get it from 
Red Hat's ftp site. 

If you want to convert packages to debian packages, you will need the dpkg, 
dpkg-dev, and debmake packages, which are available on the Debian ftp site.
You'll also need gcc, and make.

Please report any bugs to the author: Joey Hess <joey@kite.ml.org>