MYOB Exo Business has a number of facilities which allow integration into third party products.
You cannot modify existing internal workflow as such but you can add custom buttons to most screens which have the ability to launch third party products.
As you can see from the screen below you can define the two custom buttons. Notice that you also have the ability to pass the currently logged in user's credentials and the sequence number of the current record. In this example the customer's account number is 2 and as such the <current> parameter will pass the value of 2 to the external program.
In addition the MYOB Exo Business database is held within Microsoft SQL Server. As you can see in the example below (the image is from Microsoft SQL Server Management Studio), getting at the data out of Exo is relatively simple. The query returns a list of your debtors.