Hi Rowland
An IIS member Eric Lo (Ezystyles) used to do a mod service - not too sure if he still does.
I got my 40D modded by Peter Tan in Hong Kong - I squirmed about sending the camera overeas, but insured it both ways and it still worked out reasonably cheaply (approx @$289AU at the time for filter+mod+ p/h). Peter's site...
http://www.tan14.com/gears.htm
email him
Doug