[OT] Entity Modeler, how to create a many to many

Hello,
I've been trying to work with Eclipse/WOProject for my latest  
project, and it seems I can make it:)

But actually I'm stick on something which might be obvious: creating  
a many to many relationship in Entity Modeler.

I used to have to select the 2 entities in EOModeler and do "join in  
many to many", but I can't find where's that feature in Entity  
Modeler...
I know I could create the join table, etc but I think I recall a demo  
of EM at WWDC by Mike Schrag doing something like this...but maybe  
I'm wrong.

Could someone tell me how to make a many to many using Entity Modeler:)

Thanks

Xavier