Assuming that a plane is delivered in the domestic US, there are a number of additional hurdles required for the plane and the crew before traveling internationally.

Here is a quick checklist of items required in preparation.

Aircraft Requirements

• Permanent aircraft registration (white copy, not pink copy)
• Customs decal, purchased online at https://dtops.cbp.dhs.gov/
• FCC Radio Station Certificate, purchased online http://wireless.fcc.gov/uls/ or via form 605.
• Insurance - the aircraft may require additional insurance when traveling to Europe. See AOPA's European Mandatory Aircraft Insurance Requirements.
• RVSM authorizations. The local FSDO must issue a Letter of Authorization (LOA) to cover non-domestic US airspace. This would include MNPS (Trans-Atlantic, even on the "Blue Spruce" routes), RNP (Oceanic), PRNAV (Europe).
• See also Extended Over Water Operations for Mustang and Phenom 100

Aircraft Essentials

The items on this list may not mandatory depending on destination, but are nevertheless highly recommended.

• Satphone.
• HF Radio. Large over water areas mandate an HF Radio for communication. The latest MNPS guidelines for North Atlantic are moving away from HF to Satphone under limited circumstances, however HF continues to be important in many parts of the world. The HF radio is an expensive option, so it's easy to think when ordering a Mustang: "I'll just purchase the HF wiring now and could always buy the radio later." The nasty surprise is that installing the HF radio afterward is very expensive, on the order of $40,000 in labor in addition to the $50,000 or more for the radio. If the Mustang is expected to travel extensively internationally, the HF Radio should be a factory installed option.
• ADF. Many international approaches use ADF / NDB and do not officially permit GPS overlays. Like the HF Radio, the ADF should be factory installed if International Travel is expected.

Crew Requirements

In a mirror of the aircraft requirements, individual crew members also have similar requirements.

• The pilot certificate must list "English Proficient". 
• FCC Operators license, also purchased online at http://wireless.fcc.gov/uls/
• RVSM/MNPS/PRNAV/RNP Training. Both King Schools and Flight Safety have international training that can be accomplished online.
• Medical. Paid crew require a Class 1 medical - a Class 2 is insufficient.
• EAPIS registration. 

Flight Planning

Fltplan.com is a very popular flight planning site used by Domestic US Operators. It's free, easy to use, and provides excellent summary plans including winds. Unfortunately, its' international coverage extends only to Canada and certain Caribbean destinations.

Jeppesen FliteStar can be used for International Planning, including world wide. Jeppesen approach plates have a consistent format worldwide. Even though many countries plates and information are now available free for download off the Internet, the format is not as consistent as Jeppesen. Jet operators, like Mustangs and Phenoms, require FliteStar Corporate Edition, as the less expensive IFR Edition will not handle fuel planning.

See Also:

http://xpda.com/flyingtoeurope/

The NBAA has a good library regarding international operations (NBAA membership required).