Reinaldo,
Great question. I have confirmed that the Microsoft Exchange Best Practices Analyzer (EXBPA) tool will be updated shortly to reflect a check for the database size check modficiation for servers that have Exchange 2003 SP2.
As per your second question concerning how to verify if the database limits were increased: beyond confirming the registry values are set properly (remember, those values are in decimal, and the blog has been updated to show a sample screenshot of those entries), you can set the database warning buffer to warn at a lower threshold.
A test example would be to set the Database Limit to 20GB, but have the warning buffer percentage set to 50%. This way you should get a warning in the Application Event Log, at the next database size check interval, as long as the database has grown to 10GB or larger.