Urbz, The: Sims In The City Q&A

i've only got one more place left to unlock but im not sure if when i unlock this place i will be able to get darius' penthouse ? :S

i dont get how to do the cheats. Like how do you do the cheat gnome. i know that its down, l, z, r, x, left but how do you do it. during gameplay? do you hold all them down at the same time? Like no site has the details. Can someone please help me?!?