How to track *part* of unstable?

[Richard Cobbe <cobbe@directlink.net>]

Greetings, all.

I'm still fairly new to debian, so I'm not all that familiar with dpkg,
dselect, and apt.

Is there a way to track the unstable branch for only certain packages?  I'd
like to install the unstable version of gnucash.  I downloaded the .deb and
tried an apt-get install, but it failed due to a number of unsatisfied
dependencies.  Most of these dependencies simply required later versions of
packages that I've already installed---from potato.

Ideally, I'd like to be able to use dselect to grab this version of
gnucash and satisfy its dependencies, but I want to leave the rest of my
system at stable, where it is now.  Is there a good way to do this?

The only thing I can think of is keeping two sources.list files, one for
stable and the other for unstable, and switching them out as necessary.  Is
there a better way?

(Also, and forgive me for asking this, but please CC me directly on any
responses.  I've subscribed to this list and received confirmation of my
subscription, but I'm not receiving any of the list traffic, and I'm not
sure why.)

Thanks much,

Richard