Your installation can be as simple as this plug and play installation
where you can be up and running in 10 minutes or a full on installation with in-wall sensors.
Of course, I had to do the full on installation which was a playhouse I built for my two girls. The playhouse is 8x8x8, I got the plans for the playhouse here http://woodmanor.net/Little-miss-playhouse-plans.html.
My Dad built it in Oregon and then dis-assembled it and drove it down to California where we put it back together. We then poured a concrete slab for it and then roofed and painted it. Its basically a full blown mini-house with electrical, insulation, drywall, vent, TV, phone, pergo floor, etc.
The playhouse in itself was quite a project. The nice thing about building it from scratch is I was able to run all the wiring for the sensors through the walls as well as the electrical, doorbell, speaker, network, coax, and phone. Here's a separate instructable on the playhouse http://www.instructables.com/id/The_Princess_Playhouse/