Pragmatically setting property class values (or workaround)

Is there a way to set a property class value at runtime? I have a property class called "cannot_verify" that many items subclass. I want to have a poplist that sets the "enabled" property to true or false for every item derived from "cannot_verify." Alternatively, is there a way to find all the items that subclass a given property class at runtime?

I am making a data entry app that must support redundant data entry (all information is entered by two people, and then the data is verified to make sure they entered the same values--the idea being that two people are much less likely to make the same mistake). There are many fields that are "free-text" that they don't want entered by the second person, and I want to disable them.

Thanks for any suggestions.

• Brian