How to use entity_metadata_wrapper in hook_boot
Here's a solution.

Add this to the top of your hook_boot() function:

function hook_boot() {
  global $user, $base_path;
  drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);
...
}


drupal_bootstrap keeps track of what level it has been called so this trick effectively pushes hook_boot to being later in the boot process.