Do to my wife's back problem she has stated that the next vehicle we own MUST have a front passenger's side lumber support. I could not find this on the next (2011) Odyssey.
If it's not a Honda what 2011 minivan or large SUV has it?
Considering Honda deleted the power pedals (unless I missed something) I would be very surprised to see something like that. My lumbar broke and sometime in the next few days I plan to open the seat up to fix it. When I do I'll look and see how difficult it might be for you to retrofit. Just a shot.
Back the early 90's I added a lumbar support in my civic, this was a bladder with a hose connected to a hand pump (picture the ones you see at your doctor when they take your blood pressure). The bladder was slipped under the seat cover. Cost was about $20.00. Worked well.
Here are a couple of links that I found that may be close to what you could do to add lumbar supports to your vehicle.