I never tried to do this before, but got it to work, sort of ... in a weird way. (I always do text wrap that needs to go into Photoshop in Illustrator, and copy/paste it into Photoshop.)
Here's what I did in Photoshop: I made a path, for enclosing the type (L-shaped like your design). With the path still active, I clicked inside it with the type tool (on the layer, not the paths palette), and typed away. To my surprise, the type did actually fit inside the path.