[plt-scheme] Applicable operators as Swindle classes

Hello,

I've been writing some code using Swindle, and I'm curious whether 
there's a way to define a new swindle class whose instances are 
applicable.  (Like instances of <generic> are applicable, but remain 
instances of a class with slots, etc.)  I had a look at the Swindle 
documentation and the code for some clues---I was thinking I could just 
subclass <function> and set a particular slot to the lambda expression 
I want when applying an instance---but it wasn't clear to me that this 
would work.  Is there someone out there who has done this and could 
give me some tips or point me to the right place in the code to clear 
things up?

Thanks!
Will