Offline Intrepid Upgrade

[Slim Joe]

I plan to beat the stampede. Is there a way to
download the packages necessary to upgrade U8.04
-- without performing the upgrade itself?

Sort of like upgrade-manager -d --downloadonly?

Basically I plan to store (probably using aptoncd)
packages unlikely to upgraded between now and Oct.
30 (e.g. packages automatically merged from
Debian). Then I'll just torrent the release CD.