Appoint your internal Project Manager / change agent
One thing that I have learned over the years is that most human beings are creatures of habit. Change is hard and the larger your organisation, the more resistance you are likely to experience. While the complete support and commitment of your board and management team is a must have, I would like to point out the importance of your internal Project Manager.
I believe that farming out "change management" to external consultants is a mistake. Instead, it is vital to identify a Project Manager who has the respect of your staff, the diplomacy to negotiate difficult issues, and the enthusiasm to bring people along the journey.
That person may or may not be your CFO, CIO or the person that led the ERP selection group. A few years ago, when I was implementing an ERP solution for Pronto Software, the change agent was the Quality Assurance Manager; she was exceptional despite not being an IT person.
If by reading these lines you have spontaneously associated someone to the role of change agent, you are probably on the right track. If not, here are some traits of such a person.
Change agents are outgoing, not really introverted and pro-communication. They are creative people that enjoy improving things rather than manage the same stuff year after year. They are the ones that come with left side ideas, things that your average manager sees as annoyances.
But these qualities are not enough. For an ERP implementation, you need someone who is respected in your business. Someone who has strong wisdom and is listened to. Someone who can work at all levels, who is capable of grasping different points of view and get adhesion for a solution that is not compromising the expected outcomes.
Last but not least, you need someone that can stand their ground with external parties including the ERP vendor, and has the ability to turn around difficult people and issues.
Did I just describe superman? Not really - there are exceptional people in all businesses. If you can't find a change agent in your organisation, I suggest you recruit and nurture someone long before you start the ERP selection process.