How do I install a .deb package that isn't in a repository?

[Daniel Robitaille]

> I am one of those odd souls who rather likes the Opera browser.
> 
> I can download a Debian package from the Opera website.
> 
> Ideally I'd like to be consistent in the way I install packages, and use
> Synaptic to do the job.  In fact the file associations are set up so that
> Debian packages should open with Synaptic.  If I double-click the file
> in the browser I get an error message that Synaptic must be run as root.
> 
> Trying to drag and drop to an open Synaptic doesn't work either.
> 
> How do I get Synaptic to find the package?  A lone package doesn't
> seem to be addable as a repository.  Can I build a little local repository
> that just contains the package I'm interested in?  Or should I just use
> sudo dpkg from the command line?

Building a local repository is not that difficult, especially if you
keep it very simple.  I used that document to get me started:
http://www.debian.org/doc/manuals/repository-howto/repository-howto.html

That's what I did on my machine last week. There was a specific
application (with 5 deb packages) that I wanted to track down on my
Warty machine.  Wrote a little script that fetch the debs files using
wget and put them in that personal repository.  Then pointed apt
source file to it, and I can use synaptic to install/update these
packages.