Approval Workflow

I am attempting to implement this gentleman's approval workflow process:

http://blogs.microsoft.co.il/rdt/2011/11/12/microsoft-dynamics-crm-2011-workflow-based-approval-process-implementation-part-3/#comment-2823859}

I'm confused with how he is tracking the history of changes to the Approval record.  It looks like he's using the Notes associated with the Approval record, but those are not accessible through a workflow.  Is there any way to do that, or is he using a custom related Note entity?