There is, open your 16:9 content in a 4:3 project and scale to frame size.
Don't know if you are still around Howard...but thanks for this solution...worked great for me
ps in my case, I burned a DVD for client at 16:9 (720x480 ntsc) and on new TV's and DVD players and computers it looks great...but on my very old DVD player hooked up to very old TV I was getting 4:3 with both right and left sides being cropped out...couldn't see whole frame...
Sooooooo, your 4:3 solution with 16:9 scaled to frame forces my ol TV to show the whole frame...letterboxed... PERFECT ! Thanks