jQuery Form Validator - HowTo

jQuery Form Validator - HowTo

I am exploring jQuery Form Validaor (By Victor Jonsson) and already liking it so much.
There is something I am trying to do with it, but couldn't figure out how to do it yet.

Once user accesses given URL, the php page will be displayed.
There should be a button clicking on which will display error message for a particular input field.
I do not actually want to validate the input value that has been provided in this field when I click this button.  Just want to display the error/validation message or some custom message for that field.

Is there any way to do this?

Any help or direction will be greatly appreciated.

Thanks.