your best option is to create a custom meta box with-in your theme and then the user will have it no matter if he typed it once before.
// Hook into WordPress
add_action( 'admin_init', 'add_custom_metabox' );
add_action( 'save_post', 'save_custom_intro_image' );
/**
* Add meta box
*/
function add_custom_metabox() {
add_meta_box( 'custom-metabox', __( 'Intro Image' ), 'intro_image_custom_metabox', 'post', 'side', 'high' );
}
/**
* Display the metabox
*/
function intro_image_custom_metabox() {
global $post;
$introimage = get_post_meta( $post->ID, 'intro_image', true );
?>
<p><label for="intro_image">Intro Image:<br />
<input id="siteurl" size="37" name="intro_image" value="<?php if( $introimage ) { echo $introimage; } ?>" /></label></p>
<?php
}
/**
* Process the custom metabox fields
*/
function save_custom_intro_image( $post_id ) {
global $post;
if( $_POST ) {
update_post_meta( $post->ID, 'intro_image', $_POST['intro_image'] );
}
}
Hope This Helps