right method for encoding interlaced ntsc

Ok I've been trying to do a full copy dvd-9 to dvd-5 for some time now. Most of the extras on the dvd are pure interlaced ntsc 29.976 fps. I've been having a lot of trouble encoding the extras so that they will play in a dvd player. I've tried ivtc but havent been able to get it to work. I just want to know the right method to encode video of this kind.

interlaced 29,97fps NTSC!

thanks for the help 

Is there a reason for that post? Am I missing something?

You can encode DVD in interlaced mode, no need to IVTC or deinterlace or whatsoever.