[plt-scheme] A couple "Lazy Scheme" questions

I downloaded and installed the csu660.plt thing, and its's neat, though  
I've got a couple questions:

First, is it possible to just extract that bit from the rest, so I can get  
rid of the "handin" button and such?

Second, I looked at the site for more info on it, and in the class notes  
there was usage of a "define-type", but I couldn't find anywhere an  
explanation of the implied type system, that is, how to use the generated  
types and so on, so if anyone could point me in the right direction for  
those docs, I'd appreciate it, thanks.