Edit MPEG-2 Video without converting to DV

I have MPEG-2 files, originaly from my wedding DVD (which I demuxed from the DVD to a seperate M2V video and LDPC audio files) and I want to make a few changes to that video and export it back to DVD (meaning MPEG-2 compression).

Since most of my video is fine, and I want to make only small changes to my video files, I would preffer not to convert the whole video to DV and then recompress everything back to MPEG-2 again, therefore having loss in video quality... If I would create a DV Sequence in PPRO, it would natively work in DV (giving me the red line above the timeline) and would require all my video to be converted (upon render) to DV, and after that I would need to recompress it to back to MPEG-2... (I think that even if I export directly to MPEG-2 from PPRO, it would internally would first convert it to DV and afterwards will recompress to MPEG-2)

Is there a way in PPRO CS3/CS4 I could edit MPEG-2 files natively, so I won't have a red line above my timeline, and I won't need to render all the video to DV... ?
After I finish editting, I would like to export the video as MPEG-2 from PPRO, in a way that it would not recompress all areas in the timeline that I didn't change. Is there a way to do that...?

PPRO CS4 has many new native HD formats, such as AVCHD, HDV etc. Is there one that I can use for SD MPEG-2 (720x576 / 720x480)...?
Is there something similar in CS3 ... ?

Any help would be greatly appreciated !

Koby.

p.s.: I know there is the Mainconcept MPEG plugin for PPRO, that does what I am looking for, but I had many issues trying to use it, and at the end I lost hope with it...