ActiveSupport and XML conversions help needed

I am using the to_xml method on my AR object. The type for one of my
fields is timestamp and the XML looks like the following.

Thu Aug 09 02:23:14 UTC 2007

I want the format to be the xmlschema format. I am looking at the
XML_TYPE_NAMES in conversions.rb and I don’t see timestamp listed. I am
new to Ruby/Rails and trying to figure out the correct way to expand the
hash to include timestamp as an option. Also, how do I find out what
the type name would be for the type timestamp? Would it be TimeStamp or
Timestamp? The standard to_xml is good enough for me except this one
issue. I would rather not define a rxml.

Any suggestions would be great!

Thanks
CW