There may be a simpler way, but the way I would do it would be to comment out the standard lines, and just leave the security ones. For example, turn this:
Code:
#deb file:///cdrom/ sarge main
deb http://ftp.debian.org/debian/ stable main
deb-src http://ftp.debian.org/debian/ stable main
deb http://security.debian.org/ stable/updates main
Into this:
Code:
#deb file:///cdrom/ sarge main
#deb http://ftp.debian.org/debian/ stable main
#deb-src http://ftp.debian.org/debian/ stable main
deb http://security.debian.org/ stable/updates main
After you change the file /etc/apt/sources.lst, you would just do apt-get update followed by apt-get upgrade.
Why you would want to do this is beyond me though. If the box won't be connected to the net, you should still do the full set of updates when it is built.
Also, if this is a desktop machine, don't use debian sarge. Go at least for testing, or unstable. Sarge is intended for servers, and has very few of the newest software.
Peace,
JimBass