you dont need a dynamic connection for this.
you need a static connection that uses the information for connecting to the other MySQL server.
The use for dynamic connections is to create one connection file that will use different database connection details based on the domain in the address bar.
A perfect example is using localhost for testing, then uploading to the remote server. Dynamic connections allows you to specify the local connection details and the remote connection details and will use the correct one automatically.
another use would be for multi-lingual sites.
you could have an english copy of the database and a french copy of the database. and using the same connection, change which will be used by using subdomains:
mydomain.en.com would connect to the English DB
mydomain.fr.com would connect to the French version.