Sweave and paths

Is there some way to encourage \SweaveInput{foo} to find foo in a  
subdirectory of a file tree? Something along the lines of the  
behavior of list.files(<stuff>, recursive=TRUE). This would be very  
helpful at calling small modular files, such as solution sets and the  
like.

I couldn't see anything in the documentation, and I looked in the  
source code, but it seems that SweaveReadFiledoc() wants to look only  
in the directory which contains foo.

Still, I'm guessing that I'm missing something. Any tips would be  
much appreciated.

Bill