I know Ryan/Oak Cycles helped re-rake a fork for one polo player but he's off somewhere on the other side of the world now... Seem to remember it involved large planks of wood and they only managed to decrease the rake by a few mm... Those were fairly heavy duty unicrown forks, originally intended for rigid jump riding though...
There's some info here probably worth reading (and PDF link at the end) http://alexwetmore.org/archives/473.html
I know Ryan/Oak Cycles helped re-rake a fork for one polo player but he's off somewhere on the other side of the world now... Seem to remember it involved large planks of wood and they only managed to decrease the rake by a few mm... Those were fairly heavy duty unicrown forks, originally intended for rigid jump riding though...