Add body ID

If you are using the context module, it is fairly straight forward:

http://drupaleasy.com/quicktips/using-context-module-set-body-classes

Otherwise, you will need to code it in the template file, separate module or modify the .tpl files.

Also, if you're using context it may just be easier to load your files based on the page with context add assets rather than hard coding a body id:

http://drupal.org/project/context_addassets/

This might help:
1. Copy the html.tpl.php from the omega core templates folder to templates folder of your subtheme.
2. Edit the html.tpl.php and add ID like below for the body tag
<body<?php print $attributes;?> id="<?php print $body_id; ?>">
3. Create preprocess-html.inc in the preprocess folder of your subtheme and add the following code and clear the cache.

<?php
function YOURSUBTHEME_alpha_preprocess_html(&$vars) {
$vars['body_id'] = 'pid-' . drupal_clean_css_identifier(drupal_get_path_alias($_GET['q']));
}
?>

Hope it helps.

removed html tags from message