How to get the path to an x-image-url or a face for a message

Hi,

I would like to use the existing functions in exmh to get either
access to an x-image-url if it exists in a message or alternatively
if that doesn't exist use the first picon/face that applies.

Ideally I'd like to have two scripts.
One where I provide the X-image-Url line from a message and the Exmh/
Tcl helper script would download/cache that image and return the path 
to it, and a second one where I provide an email address as input and 
the Exmh/Tcl helper script would return the path to the first relevant 
picon.

I have the impression this should be trivially simple as the 
functionality already exists within exmh. I have just so far not been 
able to work out how one would do this. (This is for scripts that would 
actually run ahead of Exmh, in a procmail recipe)

Any pointers, suggestions or bits of code are greatly appreciated :)
Thanks in advance,
  Marc Baaden

NB: concerning the picons/faces, I'd preferentially use the gif version 
if it exists, and only fallback to xpm/xbm otherwise
-- 
 Dr. Marc Baaden  - Institut de Biologie Physico-Chimique, Paris
 mailto:[email protected]      -      http://www.baaden.ibpc.fr
 FAX: +33 15841 5026  -  Tel: +33 15841 5176  ou  +33 609 843217