practical question

This is a practical question related to application/foo+xml media types. 
I recognize that this is not a programming forum; I am posting here anyway 
because I think that this group will be keenly aware of the problem and 
interested in a solution.
IE will only allow cross-domain requests for the text/xml or 
application/xml types.  It does not support application/foo+xml.
Does anyone know of a workaround which would allow me to avoid having to 
publish resources with the wrong (application/xml) type?  If I do have to 
publish with the wrong type, does anyone know of a method which would 
allow me to minimize the damage?
This is important because it is a limiting factor for all XML-based 
formats.
Thank you.

-Lucas Gonze