Once you import the views and convert them to tables, delete the views. What you are left with is a bunch of tables prefixed with T_ . Now right click on the relational model in the tree and choose Change Object Names Prefix.
This is a simple dialog, much like a search and replace. Enter the old, the new, and what object types it applies to and everything is back to the base names you'd expect in a diagram.
The end result is a model of all the APEX_ views for 4.0.
Oracle Application Express Views