1) Establishing yourself as a consultant, doing a consultative selling approach.
2) Figuring out who the _strategic_ person is. That's who you need to talk to. With enterprise businesses that size, purchasing decisions are made for long-term strategic benefit.
3) "Custom" is the key word. Don't talk about what you've done for others, talk about what you can do for them. Again reinforcing #1, ask lots of questions that tease out their unique goals and position your product around those goals.