Can it be done or is it generally impossible?

I guess the dealer would have to assume your lease payments and buy out the vehicle. Or basically just buy it out from the leasor.
LOL that's $15K for my car right now which was only $22k new and it's 3 years old!

I guess it's possible, anyone ever do this?

I've done it a lot, call the leaser before and find out the payoff amount. That will give you a base to negotiate with the dearler, if you are close to the end of the lease, you should be able to get the dealer to buy it off for the payoff amount. The dealer pays off the car and you are free from the lease.