My advice, if you don't want to deal with the IVTC (which sounds like the best option at this point): Take DVD2AVI and have it output its .d2v file with plain, standard fields (not forced film, not swapped fields). Open up said D2V file in TMPGEnc. Set your field options on the MPEG2 to Interlaced. Encode. Or if you're using CCE, use MPEG2DEC to open the D2V file, feed the AVS script into CCE, and encode (just make sure the Progressive Frames option isn't checked in your Video settings). That should give you a clean interlaced->interlaced transcode.