The steps are:
1) Create a new MySQLi Connection
2) open a page you want to update
3) go to the server behaviors panel
4) Open any recordsets on the page from the server behaviors panel and change the connection to your new mysqli connection and click 'ok'
5) Open any insert, update, or delete server behaviors and update the connection
That should do it. You just run into hand coding issues if they no longer show up in the server behaviors panel. In that case, maybe hire me to work with you in a premier support ticket to manually update those sections.