First, I suggest that you clone the asset in CM, then it should be a simple matter of opening the asset for edit and changing the kuid reference for the hornsound in the config.txt file. You need to change the kuid in the hornsound tag and also in the kuid table. I don't have the Blue Comet, so I'm assuming that it can be cloned and opened for edit. Make sure that you commit after making the changes.
Mike