Adding non-ubuntu packages

[Derek Broughton]

I tried this before, and was told "don't do that", so I'll try to take a 
different tack.

I want to add a package (Mambo) from Debian experimental.  Please don't tell 
me it's dangerous to add packages from Debian, let alone from "experimental".  
I already _have_ mambo, so it's too late for that.

Is there a way to either add the debian repository to /etc/apt/sources.list 
and have it not generally checked, or to use an alternate source list when I 
want to get something from another repository?

This has the oddest result:

  apt-get update -c=/etc/apt/sources.list
  E: Syntax error /etc/apt/sources.list:36: Extra junk at end of file

Funny how the same configuration file read by default is invalid if it's named 
explicitly!
-- 
derek