Lo primero que hay que hacer es logearse como root y modificar el sourcer.list
Hacemos un
deb-src http://mirrors.kernel.org/debian lenny main contrib non-free
deb http://download.skype.com/linux/repos/debian/ stable non-free
deb http://www.debian-multimedia.org testing main
deb-src http://www.debian-multimedia.org testing main
deb http://ftp.mx.debian.org/debian/ lenny main
deb-src http://ftp.mx.debian.org/debian/ lenny main
deb http://security.debian.org/ lenny/updates main
deb-src http://security.debian.org/ lenny/updates contrib non-free main
deb http://security.debian.org/ lenny/updates main contrib non-free
deb http://ftp.es.debian.org/debian/ lenny main contrib non-free
deb-src http://ftp.es.debian.org/debian/ lenny main contrib non-free
deb ftp://ftp.debian.org/debian experimental main