mass rdf file change - how?

Hi,

With FF 3.x the mailto handling changed to a "mimeType handling
behavior", which is configured in mimeTypes.rdf.
Formely the app handler settings via about:config [1] were sufficient.
These could be predefined with MCD/autoconfig.

For new profile a preconfigured mimeTypes.rdf is not a problem.
(change, save, copy to defaults folder)

But how to change existing setting in an enterprise update process (FF
2 -> FF 3.5) the best way? We are talking about > 10.000 seats.

Are there modules for perl to use best or example shell / python
scripts to manipulate the rdf files?
Does anyone have a working one for thing like this?

I'm really stuck here.
I tried the "xml2" tool, but mimeTypes.rdf seems not to be proper XML
(because it isn't).
xml2 throws errors. :(

M.

[1] http://kb.mozillazine.org/Default_mail_client#Setting_email_client_for_Firefox_in_Linux