To make it work as a status message:

Traverse in Finder to: ~Username/Library/Application Support/Adium 2.0/Scripts
Locate the Countdown.AdiumScripts file
Right-click (or control click) on it
Choose "Show Package Contents"
Open up "Contents"
There should be an info.plist file.
Open it in something like BBEdit, or any plain text editor
Change the lines where it has /countdown, /countdays, and /countshort, to
%_countdown, %_countdays, %_countshort respectively.
Save it.
Reload Adium.
Now use %_countshort{4:30 PM} in your status line, and you should be all set.