You won't find anything on Colmax website. The problem is Do you speak French? Because often French producer don't speak English at all... But could be okay...
I know that Fabien Lafait is often looking for models
http://www.illafait.com/fabien-lafait.php (go down you will find his email address)
Also there is PornTour they shot Holy D so it's ok for English girls...
http://www.porntour.fr/casting.php
There is a French producer, Olivier Lesein, who comes to London soon for 2 days, I will meet him for a shoot for
bangtour.com. He shot a lot for Vcommunications
vcom.fr a big French porn company. Maybe if you are in London you can meet him as well.
Xstarsworld.com is a website where you can meet some producers, models, and also fans it's a bit as Harmonysocial actually but works much better
.
Sabrina Sweet an alt French porn star started her own production (Sweet production) and she is looking for models very often
http://www.sweet-prod.eu/contact.html She shot a lot of nice girls very famous now as Angell Summer
MMM100 also, they are French but they shoot in Barcelona
http://mmm100.net/1717/casting.php
I don't know any agencies in France. You won't find a lot actualy, French think you are like a pimp if you have this kind of agency (French are stupids when you see their football team you understand...)
I know only something about French porn Industry, I can't help you for an other country but hope it can help you a bit.
Kisses
Tiffany