to get these plates, your car would need to be registered to either a country's embassy or a multilateral organization like the UN, World Bank or USAID
also, i don't know if it has changed, but the "real" diplomat plates (i.e. cars owned by ambassadors and others with diplomatic immunity) have only 4 digits...service cars owned by the embassy or the UN will have 5 digits.
when we lived in the Philippines my mom drove a van with 5-digit diplomatic plates (she worked for the UN at the time)...hindi ka talaga papansinin ng law enforcement whatever you do.
of course, pinagbawal ako na gumamit nung van - no telling what an immature teenager would do with a car with diplomatic plates ;)