Make Comments 'read only' until 'Add comment' pressed?

I have implemented the code in this thread:
to ensure that people always use the add comments button and can not modify old comments. However, some users are complaining as they forget to click 'Add comments' and type in their comments only for them to get the warning and the comments not get saved.

I was wondering if there would be a way to make the comments 'read only' until the 'add commnents' button is pressed?

I can get the comments to be read only, but can't seem to get it to switch to a writable field at the right time.

any help would be greatly appreciated.