If you can get your emails to .eml format you can simply drag them into outlook.
Check out this link, hopefully it will provide a little guidance. How to Export Mail from Thunderbird to Outlook Express and Other Email Programs - About Email
I haven't use this utility myself, but I have imported emails into outlook from thunderbird by simply saving them as .eml files and then dragging them directly into outlook 2010. the mbox2eml utility (if I understand it correctly), allows you to do this by folder, which would be helpful if you have ALOT of emails you want to export/import.
If this doesn't help, please let us know, and we'll try something else...