There is a MEL script here at FXguide, that exports Maya camera data to FFI. It’s rather old (added 03/26/02), so I don’t know if it still works with Maya 5, but I believe it does.
Go here: http://www.fxguide.com/fxtips-58.html
I also found two more recent (06/30/03) MEL scripts from Secondunit’s Tom Tiller.
Here’s the link: http://www.fxguide.com/fxtips-182.html
I know you didn’t want MEL scripted workarounds, but if there’s no other solution around…
Hope this helps!