What you don't understand is that just using the MySqlConnectionString is not sufficient to use mojoPortal with MySql. It requires different data dlls in the /bin folder and different setup scripts for the database. The package you installed is configured for MS SQL.
My guess is it will be much easier on GoDaddy to use MS SQL, you may have trouble getting MySql working there, but if you weant to try please read the MySql documentation carefully. You need to download the MySql-Data-Layer package from our codeplex download page and copy the files into your installation.
But as I said, knowing what I know about GoDaddy things will most likely be easier if you stick with MS SQL.
Hope that helps,
Joe