[plt-scheme] Fostering little languages

Hi,

I've just read this article from "Dr Dobb's Journal" march issue. Very 
(very) good article by the way !
I'm in my fourth year of studies in computer science and have the 
project of developping a "little langage" on top of Scheme using 
DrScheme's IDE. My question is: where can i find *real* information on 
making a new langage pack for exemple, or just interfacing with the 
stepper or any other tool that might need some help understanding the 
new syntax.
"Fostering little languages" mentioned the problem but didn't give (in 
my opinion) a real answer...

Thanks for the help :-)

Pierre CHATEL