Having been professionally involved twice in the carve out of the business unit I was working for, some key success factors were:
1) New leadership/owner involvement during the various steps from the carve out until the post integration
2) Well structured schedule for the numerous activities with solid project management (especially on IT)
This is my view from a support function perspective only. Sales organization may have different KPI.
For me, having been involved in a carve out and part of the IMO team on the targets side:
1) ensure everyone is aware, organisation wide, why this is happening, what will happen and when – good comms will be key.
2) from a specific IMO perspective, ensure you are all clear on the goals and KPI’s to be achieved – success factors etc, start with the end in sight.
3) Agree with Jerome, depending on the business model and focus points, rigorous project management is vital.