Hi Ron,
Thank you, I am glad you like the tutorial. First of all, you need to conform to 29.97. Drop that into a sequence following the tutorial (using 23.976 , NOT 23.98! As the source frame rate), and 29.97 as the output frame rate. That means you will apply Twixtor with a speed change of 80% (which is 23.976/29.97).
The key here: make sure the sequence you drop Twixtor on is set to have lower or upper fields first as part of the sequence settings. This will tell Twixtor to create interlaced frames!
The other tutorial you should watch is the one on Marking Edit points in Twixtor within FCP
http://library.creativecow.net/articles/freitag_lori/twixtor-fcp-edit-point...