Somthing like this..please correct me if Im wrong...Im going from memory:
Ensure the car is setup to use the remote keys memory in the onboard computer.
1. Start the car with key "a".
2. Set mirrors and seats.
3. When all is set, use buttons on left side of drivers seat. Hit the "memory" button, then hit the "a" or "1" button.
4. The car is now setup for driver "a"
Now do the same with your second key, except hit the "b" or"2" button on the driver seat after hitting the "memory" button. You should be good to go...I think.
When you unlock the car with a key, it should automatically change the settings in the car to that key.