Edit: I asked this question and found the answer so I am posting it in case someone needs the solution
<a href="http://www.example.com/upload?iframe=true&width=600&height=460" rel="prettyPhoto[iframes]">Upload photos and videos</a>
This will use prettyphoto to load an external page in an iframe you control the size of and can be useful as a contact form or form processing.
Create a new thread and tell me what problems you are encountering and what you want to know. 
There is no step 3 :) 
