[Runn3R]

You can do it with public OnPlayerEnterDynamicCheckpoint(playerid, streamid)... //Without clicking a button

Create dynamic checkpoints on every entrance/doors with a stream of 5.0 so they don't show on screen the whole time..

With clicking a button check OnPlayerKeyStateChange on the SA:MP wiki.

Also you'll need to loop through all the houses/entrances when the player presses the key.