Implementing PRINCE2, or any project management method for that matter, will take time, focus and money. To succeed, you need executives in your organisation to support a project management improvement initiative.
This should be straightforward unless your organisation already has a functioning project management framework. Two things will help you succeed:
The Right Timing
Proposing a project management improvement initiative is easiest just after a couple of key projects have been perceived to fail. Bad results speak for themselves — they create a natural opening for a discussion about improving how projects are managed.
The Right People
Understand who will support such an initiative and have them with you in the room when it is suggested to other key stakeholders. Build a coalition of supporters before the formal proposal is made.