[CentOS] Using HTTP proxy for yum

> Is there a way to use an HTTP proxy (with a user/pass) with yum?  Or
> at least a way to pass a user/pass through yum?  I have a situation
> with a CentOS server behind a web filter appliance.

Add the following to /etc/wgetrc

http_proxy = http://username:password@proxy.example.com:8080/
ftp_proxy = http://username:password@proxy.example.com:8080/

... the web filter will need to be able to do http byte-range requests though. 
The proxy we have at work can't, yum should be able to deal without but can't so 
I have to rsync each of the repositories down locally and run yum from them.

Dan