yum access ftp repos without a proxy, http with proxy

I have a new situation at work were the proxy server refuses to allow 
*.rpm files to be downloaded because they are "streaming media". 
However, direct connect to the internet is allowed (bypassing the proxy) 
only when ftp is used. So I can set firefox to use the proxy only for 
http and do direct connect with ftp. This allows rpm files to be 
downloaded in firefox if they are on ftp servers.

However, I don't know the correct method to configure yum to do the same 
thing. There is "proxy" setting that I have set in yum.conf. It appears 
to cause both http and ftp to use the proxy. Is there a way to tell yum 
to use the proxy only for http access and to use no proxy when ftp 
connection is attempted?

I see a possibility of setting
proxy=_none_
which could be placed right before baseurl=ftp://.... if a list of 
explicit urls are used, or maybe after mirrorlist=http://... if a list 
of mirrors is requested. (http connections require the proxy.)

I don't have a way to test this now since my current distro (fedora 8) 
seems to only be archived on 3 http servers and not on ftp. (I can use 
an external socks server with ssh -D option to download f8 rpms via http 
using firefox but yum does not support socks connections from what I 
understand.)

Thanks,
-gene