if you have boris continuum complate AVX in your AVID then use the “De-Interlace” plugin and switch the dropdown menu to “simulate pulldown” this will effectively drop your clip to 24fps and re-insert 6 fps to give you that “telecined” look. i have used it very often and it looks fantastic. after that add a color correction of your choice to simulate the filmstock or look you desire.
i wouldnt use the stretch function in the render que really ever unless you are making stuff for the web.
i would take your 864×486 comp and drag it into a 720×486 comp set to widescreen (1.2) it will make the comp anamorphic in that it will be strectched vertically. use the animation codec and then import to avid and enable 16×9 monitoring by control-clicking in your record monitor side and setting to 16×9. also hit the button on your NTSC monitor for 16×9.
any sort of time echo type filter will do the trick.
you might also want to tweak your levels after that to bring out more of the highlights that might smear.
i believe the Boris Continuum Complete AVX has it. its a pretty great bundle of plugs. definitley worth the cash if you can spring for em.