Looking for software to create a personal hotspot on Mac OS X (not using the built-in ability)

I got my nifty little MacBook Air today. Since I will be going on travel I was hoping to use my iPad 3G as screen extension with Air Display. It works being in a shared WiFi network. Sadly Apple is a bit restrictive on the tethering with their mobile devices such as the iPad.

Now I read iOS 4.3 will enable the iPad to use tethered networks. But the feature will not be working for iPad 3G. I assume their big partner telecom companies fear everyone will quit their internet contract with them.

So I want to create a personal hotspot on my MacBook and use it on my iPad. But the iPad is not able to use this network. The network is visible but not usable.

On Windows there is this connectify program which lets the PC act as wireless router.

Does anybody know a similar program for Mac which would turn it into a wireless router? Or is there something I don't see with Mac OS X's builtin features?

1.) On your MacBook Air, open System Preferences and go to the sharing pane.

2.) On the service list left click on Internet Sharing, but don't click the checkbox yet. there are some more steps to be done before.

3.) In "Share your connection from" select Built-in Ethernet.

4.) Check Airport under "To computers using"

5.) If you like click on "Airport options" to set network name and security options

6.) Check "Internet Sharing", your iPad will find your MacBook now.