Wikipages restrictions by "custom" usergroups.

[get]

in order to have a good populated wiki on the office, we are trying to import all our documentation about projects and clients to our new trac wiki. This documentation has to be accesible to all of our office, what is already is, what we need is a custom userlist and user manage panel, where to define what user or group can access to what wiki page or wiki category.
because, there will be access to the wiki from our costumers also, in order, that themself can update their project wikipages. But they can't access to our own wiki.

Also, if there is any plugin or similiar hack avaiable, pls let me know about.