Don't recall seeing a plug and play solution. You have a source you can at least pass along for review and opinions? Without it I am not sure you're get a lot of bites. That being said, I'm wondering why the mod? What benefits do you expect and at what costs (financial and otherwise?)
Not sure it really applies, but I have rear air suspension on E70 as it came as part of the three row option for X5's. I wish it had standard suspension cuz other than knowing I will have to spend $398 and an afternoon of my time crawling under the car to replace the air bladders sooner rather than later, I struggle to find the difference with standard suspension.