A missconception is to thing that Parsley should handle ALL messaging. Parsley's goal is to help you decouple your application. Decoupling is good to an extent, and Flex 4 (Spark) already let's you separate the logic from the View layout.
So you do not have to use Parsley's messaging for everything. Just like using Signals for everything isn't the best idea.
If you have a view that needs to communicate with models, commands, services, other views, etc... then you can have the view's event handler, dispatch a Parsley event.
Check out
http://artinflex.blogspot.com/2010/09/quick-dive-into-parsley-basic-messaging.html
for the basics.
Also in case you wish to have Parsley manage Flex Events then also check
http://artinflex.blogspot.com/2010/09/quick-dive-into-parsley-messaging-with.html