Maybe it's a bug. Try e-mailing their support address to report it, or post it in their <a href="http://forum.alcohol-soft.com/index.php?showforum=4">bug</a> forum?
Alternatively, you can go hunting in your registry as you suggest. Install a program that watches the registry (or takes snapshots), and then install Alcohol. Then compare the snapshots. I think <a href="http://www.sysinternals.com/Utilities/Regmon.html">Regmon</a> does live registry-watching.