Rated 5 out of 5 stars
How to make it work with TB5
(from bmdb on https://addons.mozilla.org/fr/thunderbird/addon/ileopard-mail/)
For those who want this to work on TB5. Save the theme to your hard drive. Go to where you save the theme and open it with 7-zip or IZarck or Winzip etc. Now to the the Install.rdf file and choose edit. Now find the line to Thunderbird that shows maxversion and change it to 7.0 and save the rdf file close the archive and choose to update the archive when/if prompted. Now go to TB and choose addon manager and choose to install from file and navigate to the save theme and install it...it worked well for me. Good Luck.