CSV can be quite useful for export to MYOB. One thing that helps is that MYOB likes to have a blank line between individual entities in the export. The Virtual List technique is quite useful here, since it makes it easy to create blank "records" in your export file.
So what you need to do is work out what fields MYOB is expecting and build a Virtual List table with the requisite fields. Once you have this table, you write a script to generate the data for the export as a global variable, adding a blank line after each entity, then just go to the Virtual List layout and export the number of records you need.
That's a very "high-level" description of an approach that does the trick. If you want any more detail, I'll expand and clarify.
AccountRight, and all MYOB products I believe, allow access via ODBC also.
I don't think you can use a direct ESS connection, but you should be able to import/export data through the ODBC connection.