Can't be done in a single pass unless you want to just change the frame rate which would change the total length of the video.
Adding 3:2 pulldown can only be achieved through interlacing. You could then, on a second render seperate the fields. The resulting footage would have a regular pattern of soft frames where two fields, each from a different frame, are blended together into a new single frame. The amount of the bluring depends on the motion withing the frame. The video would not look as goos and ad standard 3:2 interlaced video from a 24 fps source.
Interestingly enough this brings up an interesting debate on film look and fps. When we were producing commercials for large ad agencies on 35mm film I always ran the camera at 29.97 frames per second and never at 24 because the resulting commercials just looked better. Sure, the broadcast video was still interlaced, but both fields were identical so we were really creating 3Op footage. It also sill looked like film because, well, it was film.
The biggest question that your question brings up in my mind is why would you need to or want to do this? I can't figure out why 3:2 pulldown video would be unacceptable.
thanks for the reply, really quite informative as to the depth of the issue.
i'm curious about separating fields and blending them, i guess i'll do a search on how to do so.
All you have to do is render your 24P project to 30I by introducing 3:2 pulldown then open up the rendered file, separate fields in AE then render the file without introducing fields.
I still don't know why you "Must" have 30P footage from your 20P source.
30fps was just the frame rate I was told to output to.
Thank you for the followup!
Unless the client has a specific need for progressive footage send them the standard 3:2 pulldown interlaced 29.97 fps render. That's what every film to tape (24 fps to 30fps) transfer has been for the last 50+ years has been and still is.