Usually the best thing to do is re-contact support and ask them to escalate the case to a higher level. Have they reached that level? It would involve people actually linking up with your machine most likely.
As it's the weekend I don't know if anyone will be patrolling here until Monday, but that's my suggestion for now. Meanwhile it might help any McAfee person reading this if you posted the case ID numbers from your contact with Support.
It would also help to know details of the operating system, service pack and how you connect to the Internet. Also, what product is it that you are trying to install?
Could you please let us know what exact issue with McAfee installation on your computer? Are you getting any kind of error message?
Also it’d be fine, if you give information about your Operating System installed along with Service Pack and internet connection.