Hi DM,
MB is kindly using the 'UPLOAD' link found on the main site. (Covered in detail in the FAQ and a visual tutorial in the Help section.)
He's been extra nice to even follow existing naming conventions for each title so it means the very least amount of effort for moderators to add his scans. Astrp3 uses the same method.
The only drawback for uploaders is you can only upload a single book at a time but speaking as a mod I certainly appreciate MB and Astrp3 using this method.
All these books are now online.
Enjoy!
-Yoc