I have been playing around with client scripts trying to see if it was possible. I read through all the docs and it looks like it isn't. 

Here's what I am looking to do:

Whenever we create a contact they are ALWAYS associated with a deal.

So instead needing to do work twice it would be nice to have both create forms together,

My thoughts were that inside of the create deal page there could be a check mark that would show the contact creation form as well. Then client script could be used to avoid any duplicate entry.

If there isn't a way to do this I will create a duplicate of all of the contact fields in the deals that are hidden by default and will use the apis in client script to create a deal before submitting. That doesn't seem like a great solution though, is there anything that would be better?