I cannot being to rationalize why you need such a process. I have had several DBs setup in my application, ie (local, stage, live), but that is all controlled by the environments setup. For example, if I access mydomain.local, then CakePHP uses the local environment setup, etc.
I think it can be accomplished, but you would have to add some logic in the
app.php file. For example
db000.yourdomain.com could use the DB000 database.
If you explain further on how and why you need this, I can try to provide more help.