He may know of potential workshops or be willing to demonstrate the process.
At the http://www.collodion.com/forum/default.asp forum a couple posters from Wales and England have today enquired about potential workshops and Quinn Jacobson has responded that he may offer European workshops shortly after his move to Germany this summer. Perhaps he will see this post here and provide more information or point you to another source. I believe Scully and Osterman have also held wetplate workshops in France. You can contact them through the http://www.collodion.org website.