@BaptismOfFire:
You seem to be on the right tracks but be very careful not to make any typing mistakes (and remember to run "apt-get update" after editing the sources.list). Sometimes local Debian mirrors can be temporarily down, in which case you may have to try an alternative mirror.
@craigevil:
All Gnome 2.10 packages should now be available in the official unstable repo. I've heard people saying that it's still a bit buggy but should mostly work OK.