I think we have a few different overlapping issues here. One is, can you (anyone) import video into iMovie 6, and maintain the original size, with no scaling?
I did something similar without buying QTPro (no budget). Did a "share" and used "expert settings". It seems to lose some image quality. And still would love
I haven't done it, but my thought would be to produce a "normal"-size movie in iMovie, and then use Quicktime Pro or similar to shrink it to the desired size.