[ESS] How to include ESS in site-start?

[David Reitter]

Hi,

I was wondering what the correct way is to include ESS in a site- 
start configuration, i.e. for a large number of (potential) users.  
There, ESS is only to be loaded on demand. By that I mean that I  
don't want it to slow down startup.

All other common Emacs packages are happy to be autoloaded. (This is  
for GNU Emacs, in particular: Aquamacs).

Thanks
David