Starting with 0.9.74, my ChatZilla packages support the same software update system as Firefox and Thunderbird.
The following cases are blocked and won't receive updates:
The check for updates occurs once a day - the /update command can be used to trigger a manual check. Updates will always prompt before download or install.
There are three update channels, based on the colour system that all ChatZilla releases follow:
The channel setting defaults to yellow and is kept in the channel-prefs.js file.
When I want to build an update-enabled ChatZilla, I run "UPDATE_CHANNEL=red ./makexpi.sh". This causes makexpi.sh with my patch applied to run:
../../../tools/update-packaging/make_full_update.sh chatzilla-$VERSION-$BUILDID.mar xr-tree
The script used is from mozilla/tools/update-packaging, in mozilla.org CVS and requires mar.exe (or equivalent on other platforms). If you don't feel like building it yourself, there's a Windows binary here.