We can try to chat by email (
[email protected]) but it will be difficult to provide the same level of information. Opening the case is the worst part. Many customers have reported that they take the insulator we provide with the DIY kit and they use that as a template for where to cut the case. The lid of the case is approx 3.3mm thick so you have an idea roughly how deep to cut. As long as your friend properly handles the circuit board the job is not horrible. As Amimoto said the worst part is getting the old cells out of the case because Segway used an adhesive to hold them in place.
I attached an image of a Segway NiMH battery that we just cut open this morning. Maybe this will further assist you in your decision on how to proceed.