[plt-scheme] r6rs define-struct and gensym

Hi,

I am trying to port an OO-lib I wrote in PLT, SchemeTalk 
(http://smallwiki.unibe.ch/SchemeTalk), to r6rs; I'm having some 
problems with trying to load gensym and define-struct.

I have found define-struct in (scheme private old-ds); but I guess I 
should use something else in the future?

And how can I include gensym? I don't directly find the exact package.

cheers,
Toon Verwaest