Hello Juan-
The official answer is we only support removing mime types, not the addition of them to the internal mimetypes.conf file. The reason is simply that we have tested the list that currently exists to work correctly with the compression engine. If there was a protocol that was not RFC compliant that was added, bad things could happen (core dumps/stalls/etc).
Send me a message to chrhiggi@cisco.com. I can help you to modify the internal config file. If you were to do something like this, aside from being unsupported by TAC as stated above, you would have to agree to/understand the implications of the change on a production box.
Regards,
Chris Higgins
