Writing a value to a field from JavaPX

I added a few fields to the Affected Items tab for an ECO. Using JavaPX, I would like to populate these fields with values upon the creation of the ECO. Preferably I would like to leave these fields as readonly but I received an error when I tried to write to it. Here are my questions.

1)     Is there a way to write a value to a readonly field?

2)     Is there a way to write a value to a field that the user does not have the rights to see the field?