[iBook] Importing emails from Thunderbird to Mail.app

[Wai Lee]

When I try to import my emails using the mail.app built-in function it 
ends up skipping a lot of emails.  According to a discussion groups on 
the Apple website, I understand that this is a problem with the 
program.  There is a posting of a script 
http://www.macosxhints.com/dlfiles/clean_moz.txt that is suppose to fix 
it, but no mention of how I go about using it.  Can anyone offer some 
insight for me?

Regards,
WL