You can convert the charset on the mySql database itself using the following:
<cfquery name="convert" datasource="yourDatasource">
ALTER DATABASE yourDatabase CHARACTER SET utf8;
</cfquery>
<cfquery name="convert" datasource="yourDatasource">
ALTER TABLE yourTable CONVERT TO CHARACTER SET utf8;
</cfquery>
Run the alter table statement on each table.
I'd suggest making a backup of the database, just in case, but I've used this on production systems to solve character set issues, and it's worked out well for me.