batch processing

Can anyone think of a way to batch process a bunch of 16x9 HD clips into identically named 4X3 letterboxed PhotoJPEG clips?

Quicktime is scriptable and Automatable, but I don't think it can put a 16x9 frame inside a 4x3 frame. FCP can do it, but it's neither scriptable nor automatable.

Any ideas much appreciated...

Thanks.