Now back on my old PC I remember there being some cheat or maybe trainer/mod that allowed me to pop in a number to place any building what so ever, even individual instances of a residential, commercial, industrial, etc ... I don't mean zones, but like I could specifically choose to say ... place down 'Rock Bottom Terrace' or 'Crazy Larry's Family Flea Market'.

Does anyone know what these was? how to access it?

Yeah. Power, Gifts, Garbage, Landmarks.