Short term, can't help. Long term, scrap McAfee and go with Symantec Enterprise. Heck even with TrendMicro I can install, configure, and manage the clients from a management server.
Then you can install, configure, and force updates and scans all from a management server, and do away with this login stuff.
One of the features I loved about Symantec Enterprise was that I could configure the client so that the users couldn't make changes to the client configuration, or even stop a scan of their PC from happening. (had a bunch of sales guys that would cancel scans if they could).