keyless entry

i have a 2000 malibu and it has power door locks and power trunk pop. but i do not know if it ever had keyless entry, how would i find out if it had it and if it dosent how do i add it to the car?

Thanks John

Take a look at the Left Hand IP Junction Block underneath the Endcap of instrument panel (driver side). How many door lock relays does your vehicle have? If it has 3 (including Driver Door Unlock) then your vehicle had keyless entry. If only 2 then it didn't have keyless entry.