Preload Errors Messages On Form Before Initial Submit to facilitate client-side error checking

Hi,

I want to load the array of form element error messages on an initial page render so that I can both populate a javascript object and so that i can convert my inputs into something like this:

<input type="text" rel="ERROR MSG HERE" class="CUSTOMCLASS" name="foo" value="bar" />

Currently the array of error messages is only available post submit, and only if an error occurs, AFAIK.

Can anyone suggest a snippet to include on a template such as "page-user-register.tpl.php" to accomplish this task? Is there a way to add the error message values in a form pre-processor such as "THEME_preprocess_user_register", which I'm already using???

Thanks in advance,
John