You can very likely clone your ECU to a used ECU. People do it all the time for BMW cars ... so you should be able to do it for the SUV's. You can also send your ECU out for repair as well. A buddy of mine is having his e46's ECU repaired now. There's lots of companies that clone ECU's.

How did you get an extended warranty for a vehicle with a CEL? Did you purchase it through the dealer?

IMO ... this dealer sounds shady, regardless of his willingness to fix the car .... it's still within the 30 day period so he is obligated to by law under your 30 day warranty. He should've never sold the car with a CEL in the first place. Don't let things go too slow on this, as after the 30 days this dealer is no longer obligated to do anything else. Since you purchased the vehicle knowing it had a CEL, regardless of what the dealer said might be the cause for the CEL ... any issues are ultimately on you. It's now your car. I would not rely on being able to use the warranty for the CEL after the 30 days either.