Symptoms

When using K2 Studio to add a Smartforms Client event a instruction field is added to the form that is not editable.
 

Diagnoses

This field is Read-only as it is supposed to provide instructions on how to complete the Task item. It is editable at Design time, and Read-only at Runtime.
 

Resolution

This field can be customized via K2 Studio at the Activity Level.

Edit the Activity you want to add instructions to (By double clicking it)
You will see the Activity General Properties screen.
The Description field here is the same as the instruction field in K2 Web Designer.
You can put whatever instructions you would like in this field and redeploy the workflow. Your instructions will show up in the User Task.