It most definitely seems like you should be able to do this since the layout of the details is very similar to the layout of the details on every other object. However, I've found no way to display the custom form in the details using layout templates, project templates, or anywhere else in set up. Obviously you know you can see the custom forms in the left hand list of navigation...I think that's the best there is right now.
Unless someone else knows if this is possible...If you submit an idea for this to be a Workfront function I'll absolutely upvote it.