how to install suse via http proxy?

I can install suse via direct ftp access to ftp.mirror.ac.uk with no problem. But now I am behind firewall with only http proxy. With boot disk I can see it loading data into ramdisk from ftp server and load GUI. The major problem prevent me from completing the installation is the error msg: Software Cannot read package data from installation media. Media Error? For god sake it's suppose to be a ftp installation. I tried different ftp suse download servers, all have the same problem! I guess this is because it can't read the packages (or at least the list of the packages) on the ftp server. I've searched everywhere for solution. Please help! Regards, Kai