First, ITIL is never "implemented." ITIL, as you mentioned, is merely as set of books that we call a "Library." This library of books includes guidelines for managing, supporting, and designing IT Services.
The Service Management processes can be implemented across an organization using ITIL Best Practices as a guideline.
Second, Service Management processes can (and should) indeed be implemented as a project with multiple phases.
There is no need to implement all processes at once. As a matter of fact, doing so will only lead to "ITIL fatigue" and ultimately, failure.
Third, implementing Service Management requires a huge organizational shift in thinking. Trying to do so without considering this very important point will probably go nowhere.
I always recommend to my clients that creating buy-in (at all levels of the organization) from the very beginning is critical to the success of the program. This should include input from HR. One of the most important factors of organizational change is the reward and incentive system within the organanization. Ultimately, people are motivated by how they are rewarded. If they are not rewarded for adopting the new process strategy, they will not follow.
Lastly, as the ITIL approach to Service Management is a means to an end rather than an end in and of itself, the rationale for moving toward the adoption of ITIL best practice must be clearly aligned with the overall goals and objectives (strategy) of the organization. This enables the ability to creat meaningful measurements of the progress of the effort.
These measurements help to mark progress toward achieving the goals and help to demonstrate to all involved that the effort has been beneficial to the organization.
For more discussion on this topic, please email me directly at firstname.lastname@example.org
Keep Up with TechRepublic