Enlist appropriate key leaders for each of the key milestones. Use the original leaders to identify candidates for the next tier. Help the Milestone leaders select their teams , using the same principles. Decide what each job requires, than figure out who could do that well. Help each key leader and team fill in the details for their respective area , modifying their part of the plan as they deem appropriate, while maintaining consistency with the overall objectives and with the plans of other groups affected.
Participation is the key ingredient in building commitment to the plan.
Get to work. Observe and Adjust. It is a very rare plan that doesn't ever need to be changed. Failure to systematically compare results with expectations and to make adjustments based on learnings is indicative of bad leadership. Celebrate the victories along the way .