Iphone wifi question

[betafoil86]

I was wondering if there is anyway to set up the iphone so that when a particular known network appears it automatically disconnects from the current network and joins the new one? What I am trying to do is make it so that when i create an ad-hock network on my macbook the iphone joins it to use air sharing pro. This would allow me to have only one shortcut on the desktop to mount the iphone as a network device, since the ip would always be the same. I was also wondering if there was an easier way to create a secure ad hock network with the same setting every time on my macbook?