I would love to import the Ultimas to boxer on my MAC however they are in windows format here on GOG.
How can I get them to import in boxer (DOS Box)?

All the DOS Ultima games are already bundled with Boxer, you need to download the "Mac Installer" from your library.

You can then double-click the app and the custom-bundled Boxer will launch. If you want to use it in regular old Boxer you have to get the gamebox out of the app. Right-click the app -> Show Package Contents -> Contents -> Resources and among all the files you will find the gamebox, it's file extension is ".boxer"

Ultima IX on the other hand is a Windows game and won't run in DOSBox anyway.