I think you'd have to install the DNxHD on both your PC and also the Mac, which was why I didn't recommend it.
It's really best to test before presenting things. Most likely both the mp4 and the quicktime file would work on the mac (internally they're both h.264). I'd bring both, and maybe there's another generic quicktime file you could bring too, just in case. Like Motion JPEG, maybe?
Vegas comes with the codecs to create all three of these as long as you've installed Quicktime, but you might also try making the encodes in handbrake using one of its default templates.
render to QuickTime, and try PhotoJPEG codec for visually lossless (use 100% quality).
if you need pixel-accurate quality, use the PNG codec, however
1) the render will take w-a-y longer,
2) the file will be 2-3 times larger,
3) the Mac will need to be more powerful or the file will stutter/choke on playback.
MotionJPEG is good if you need to preserve interlacing.