How do I get GtkSourceView to recognize a mime-type

["John Anderson" <sontek gmail com>]

.ashx is a file extension for an HttpHandler in mono which means it can
be in multiple languages (C#, VB, Boo, Ruby, Python, etc) and I was
wondering if there was an easy way to get gtksourceview to recognize
this file extension and highlight it. Since I'm mainly a C# developer I'm willing to settle for C# highlighting this is what I did:
copied csharp.lang to ashx.lang and then changed its mime type to
application/x-ashx which gnomevfs-info told me was the type to be
defined.  Yet when I open up gedit with a .ashx file it doesn't
recognize the file by default and I have to view->highlighting
mode->ashx

I have 2 directories for mime types /usr/share/mime and /usr/local/share/mime     not sure if that would be causing this glitch.

Is there anything else I need to do?

I'd also be willing to do the work to get it to allow all CLR lanagues if this is possible.

Thanks,
John