I don't think he wants to clean the hardware, but prevent any more gold plating from disappearing.
Any rubbing of the gold plating is going to remove the gold plating. I would remove the gold plated hardware and store it until you re-sell the guitar.
Your best bet may be a carnauba wax, like Meguiars.
All gold-plated hardware is problematic on guitars because the plating is extremely thin and doesn't stand up to even normal use.
I would add to the complaint by stating that the chrome or nickel plating on PRS guitars is crap as well. My McCarty is only a few months old, and already the hardware looks like my 25 year-old Les Paul. Very disappointing for a $2000 guitar. :x