After reading that the HTTP_PROXY variable is used by yum, I edited the variable to the proxy of choice (with port number) and yum still doesn't work. I then edited the yum.conf file with 'proxy=http://example.com:80' and still no luck.
Firefox works fine with it and I've checked the mirrors and files are there, however it keeps coming back with:
[ser@fed-full ~]$ sudo yum install make
Loaded plugins: refresh-packagekit
Could not retrieve mirrorlist http://mirrors.fedoraproject.org/mir...a-10&arch=i386
[Errno 14] HTTP Error 404: Not Found
Error: Cannot retrieve repository metadata (repomd.xml) for repository: fedora. Please verify its path and try again