You could try to do this, parabel, but it's not a really good idea to over-compact. How about writing yourself a little AppleScript that you can schedule in iCal ever few weeks?
If you really
must do this in SD!, you'd want to use a shell script like:
Code:
!/bin/sh
nohup /bin/bash -c "sleep 30;hdiutil compact $6" &
Basically, this put a background process in place that waits 30 seconds, then compacts the image. We wait 30 seconds (and go into the background) because SD! isn't done with the image when the after copy script runs. So, we wait 30 seconds to try to give it a chance to complete. $6 is the 6th parameter to the script, which is the name of the image file being processed. See the User's Guide for more information...