You might start by looking here:
MIMA Honda Insight Modified Integrated Motor Assist - Is it too late? I think not if we act now Mike's the guy that developed the MIMA controller for the Insight.
It shouldn't be impossible for some good electronics types to do the Lion swap. I think basically you'd have to run a microprocessor in between the stock battery controller, and translate the readings - that is (simplisticly) if the stock battery pack has X KWhr, and a Lion pack 2X, you'd divide everything by 2.