This has been identified as a product defect and is being tracked as Defect ID 762697.
Create and follow the custom command setting as shown in the SDK.
Active Roles SDK > Web Interface > References > The Commands Settings
In the script provided in the documentation 'GetEx' will not work as stated.
allowedAttributesEffective = objCommandContext.DirectoryObject.GetEx("allowedAttributesEffective")
Enhancement request number 762697 has been submitted to Development for consideration in a future release of Active Roles.