How to join two Drupal CCK content types in view without a node reference field, fast?
Since you don't have a reference between the two, Views has no way of knowing how the node's relate to eachother. Views has no direct support for joining on arbitrary columns.

So to solve this, you need to declare the relationship to Views your self. You do this by implementing hook_views_data, or in this case, since Views has likely already created most of the array, hook_views_data_alter. The documentation for the first function has an example with code for a relationship.