OK, it's the Christmas season, so I'll give a hint.
- cnID must be equal in both files
- hdvd tag must be set to 1 in the HD file
- stik must not be 0 (Movies), set it to 10 (x0A) (TV Shows)
These files will import into iTunes combined, but listed in TV Shows. Use the iTunes "File Info" option to change it to Movies. We haven't been able to figure out why iTunes will not combine the titles if stik is set to 0 (Movies). I now have a couple movies with combined entries in my iTunes movie library.
At this point, I'm not willing to give exact specifics on how to do this; either figure out how to make these changes yourself, or wait for a program to be released (it is currently being worked on).
Special thanks to those who figured it out...