Setting the mimetype for a XSLT sytlesheet

My files work fine with three browsers, IE6, Netscape 7.1, and Firebird 0.7
on my local machine.  When uploaded to my web server, I get the "Error
loading stylesheet: An XSLT stylesheet does not have an XML mimetype: (my
XSL file)".

How do I specify the mimetype so that all three browsers will display my
pages from the web site?

I've searched the web and found only confusion.

Chris Kimball