I just went to the petronas counter (sg.besi - puchong bypass) and paid rm 2 to reload touch & go using amex 

here's the map (credits to Ronnie): http://goo.gl/maps/2qQNx
it's near to Sunway. take the Sunway LDP toll heading to Puchong/Bukit Jalil. After this toll, keep left to take the exit heading to Bukit Jalil. Immediately keep on the left lane, cuz Petronas is on the left side already.

You may not be able to turn to Petronas immediately due to fast incoming cars. There's a small entrance slightly after petronas, that goes thru and around the back of shoplots/houses. you'll reach Petronas from the inner road.