Have just ordered a Chromecast and thought would entertain myself whilst waiting for it to arrive by reading up on how to set this thing up.

Looking at the various guides out there it all seems quite straght forward to me with one exception: The chromecast has no keyboard/mouse/input device of its own so one must set it up via another deivce such as a tablet or windows PC, thats OK but how is the "other device" supposed to communicate with the chromecast? If the Chromecast is connected to your Wifi network then yeah, it communicates via the network but how can you do that before you have set up the Wifi on it? You need to tell it which Wifi network to connect to, type of security, password etc before it can connect to the Wifi and without the wifi you can't give it that information right? What am I missing here? Will I need to temorarily disable the security on my router to get the initial setup done?

I guess to summarise: how can you connect the Chromecast to your Wifi network when the Wifi network is needed to be able to do that in the first place?