To get starting you must know what does the magic. Adobe Labs has started Adobe AIR® Packager for iPhone that offers the technical capability to have ActionScript 3 projects run as native applications for the iPhone 3.0 OS.
Adobe AIR® Packager for iPhone accelerates Flash conversion to Apple format (ipa). The '.ipa file extension stands for 'iPhone/iPod Touch Application' and is essentially a compressed data archive that is readable only by Apple devices.
Step 1 – Downloading the Adobe AIR® Packager for iPhone
Use a Winrar or similar utility to extract all files to a folder (eg: C:\ipa)
Step 3 – Register as Apple Developer
To be able convert any Adobe Flash application you must have a digital certificate provided by iPhone Dev Center website (http://developer.apple.com/iphone/). There you can do the following:
Apply to become an iPhone developer.
Manage and create iPhone development certificates, provisioning profiles and app IDs (which are defined below).
Submit applications for the App Store.
By the way, you can go ahead on 2 ways:
Register as regular Apple Developer (for iPhone Program costs US$ 99,00/year)
Use a digital certificate file from a colleague (share the investment)
iPhone development certificate: used to identify a developer for the purpose of developing applications. You obtain this file from Apple once you are registered as an developer. Later you convert this certificate to a P12 certificate file to sign the iPhone application you create using ActionScript 3.0.