Data Migration for Microsoft Dynamics AX 2012
Partick Nelson recently made a Dynamics AX Data Migration white paper available on InformationSource. Data Migration for Microsoft Dynamics AX 2012 includes sections on import via the Excel Add-in, import via RapidStart, using AIF document services and custom code, and an example of using AIF to import global address book data.
Once you've had a read of that whitepaper, go back and check out the other content that InformationSource has to offer... it is a fantastic resource.