[plt-scheme] servlet development, again

How are module servlets developed in DrScheme?  According to the 
documentation, develop-servlet.ss should be used, but as far as I can tell 
this file doesn't exist (this has come up on the list before, but I haven't 
seen a response).

I thought that if I opened the module, added the servlet teachpack, pressed 
execute and required the module, that then I could do (send/finish (start 
initial-request)), but this won't work: "expand: unbound variable in module 
in: request-bindings".  None of the request accessors are bound in the module. 
  Requiring servlet.ss & servlet-helpers.ss are no help either.

Thanks,
David