Agile methodologies (such as Scrum and XP) heavily rely on the customer’s participation in the iterative development. The concept of Lean startup would not apply well in the IT Lean concept unless you have the customer with you during development. Especially for enterprise implementations it is common for an Agile implementation/integration team to kick off a “war room” and do the customizations on site with the business customer. There are a few pre-requisites for this to succeed but if you are truly interested in the topic I would recommend you check out my friends at http://www.lithespeed.com (Arlne Bankston and Sanjiv Augustine) who are in my mind world experts on the topic.

Hope it helps
Dror