sysinstall, ftp & proxy

[vdm.fbsd at virgilio.it]

I run freebsd 5.4. 
At office I compile my ports of interest smoothly, like a charme with a
mere "make install clean" from behind a proxy which I have once and for
all defined in /etc/make.conf as in these 2 lines:

FETCH_ENV = HTTP_PROXY=http://userid:passwd@proxy.domain:8080 
FETCH_ENV = FTP_PROXY=http://userid:passwd@proxy.domain:8080 

In a nutshell: no problems!

INSTEAD ... 

When I run sysinstall and want to download some sources from ftp.it.freebsd.org,
it seems (and it is logical) that the make.conf is of no help. 
In fact, when I click the media, selecting FTP I'm faced with at least 3
solutions:
FTP server
FTP passive
FTP behind a proxy

and none of them seems to ask for something like userid:passwd at proxy.domain:8080
but at most proxy.domain:8080.

What FTP server should I select and HOW should I set the proxy with userid
& passwd up?

Ciao
Vittorio