Jeremy, the easy way to change the CV's is with out the Digitrax decoder in the Blue Line. I have a PK SD 8 that shell just lifts off, I change the motor control decoder in it. For the Blue Line decoder, you must use Pd Direct Mode.
I know it sounds like a pain, but it is simple.
Cuda ken
I hate Rust
The best info can be found on the Broadway limited forums here:
http://www.broadway-limited2.com/forum/viewforum.php?f=1&sid=ef188a1f9122faa144953a7e012ff47e
Springfield PA