How can I debug CRM 2011 workflow using the plugin registration tool?

I do this with plugins, and it is really useful because you do not need to bind to the IIS process.

This guide explains how to do it locally: http://athulmt.blogspot.it/2012/09/debugging-plugin-in-crm-2011.html

Now I'm trying to debug CRM 2011 workflows using the plugin registration tool, but I haven’t found a way to do this because I don’t know the workflows.