OK here are the steps as best I can recall.

1. Install Perl
2. Give the IUSR account Read permission on C:\Perl\Bin
3. Add .cgi to the list of application mappings (using the same settings as .pl) to the Master Properties of the WWW Service. It's on the Home Directory tab behind the Configuration button.
4. Create the MT directory and assign READ NTFS access to Everyone. IIS Permissions should be Execute: Scripts and Executables.
5. Create the MT\DB directory and assign FULL NTFS access to Everyone.
6. Copy the MT files to the MT directory.
7. Modify the CGIPath.
8. Modify both the Datasource and TemplatePath in mt.cfg to point to the right directories. Should be in the format C:\Inetpub\wwwroot\MT\db
9. Run mt-load.cgi and then delete the file if it's successful.
10. Run mt-check.cgi and load additional modules as required.
11. Create (if needed) the directory for the blog and the archives.
12. Assign FULL NTFS to Everyone to both of these directories.
13. Run mt.cgi and login.
14. Edit the profile.
15. Create your first entry and see the results!