Why do you want your own DB ID? I have my reasons, most center around being a control freak but I"m curious why you do?
Don't get hung up on the term "Owner", it's your configuration.
Using Autodesk's ID should not prohibit you from using this configuration in Revit. The ID is really meant to prevent Revit from mix and matching multiple configurations in a model. As Revit is parametric, they want to ensure as much as possible (as difficult as it is at times in Fabrication) that things don't break.
The only real technical risk if using Autodesk's DB ID is that over time, your config changes from the default Autodesk shipped. Anyone else using a config based off of the same you started with could load their config into your model however their config could now be considerably different from yours. Small risk but it exists none the less.
But to your question...If you want to assign your own ID, you'll need to go to the DATABASE folder in the config and delete/rename the "SETUP.MAP" file. When you restart CADmep, it'll recreate that file with the default settings one of which is the DB ID which you can then assign.
Doing this will wipe some other settings. At quick look, it appears that anything under Edit Database -> Configuration -> Configuraition is stored in this file so you'll want to capture/recreate those settings when you do this.
I also have notes that this file also controls which machine is "default" in your CAMduct configuration (and easy fix).
There could be any other number of things that get lost when swapping this file, it's darn near impossible to check everything but I'm fairly certain this is most of it as the file is fairly small. Keep a backup of the file in case you find an issue later.
Note, any project you've already started in revit that uses the ID Autodesk has, will need to maintain that. I'd recommend copying the entire configuration and making a new one that you perform this process on so you have a new configuration for anything new going forward, plus your old one for anything existing.
However, I would suggest that this isn't entirely needed. You should be able to use Autodesk's ID without an issue. I have my own only because our legacy systems existed before this was an option.
