[plt-scheme] drscheme 202 on mac os x --- can't connect to update server

I am running 202 on mac os x 1.1.5, and I'm behing an http proxy
the proxy is set in both the network setting of system prefs and in the 
environment variable http_proxy

I can't connect to the update server (Help -> Check for Updates), and I 
can't find a place to enter the proxy in the preferences dialog (unlike 
the Windows version).

I would be grateful for some help.


Cheers

Chris

Dr Chris Wright
Medical Director, ICU
Monash Medical Centre
Clayton VIC 3168