I didn't use the custom tag editor to build this, but this should work...
Code
<?php
$export_tags = array (
  0 => 
  array (
    'tag' => 'shutterfly',
    'descrip' => 'Shutterfly Image URL',
    'prompt' => 'Please enter the URL of the image you wish to embed.',
    'regex' => '([a-zA-Z0-9-_]+)',
    'markup' => '<img src=\\"\\\\\\\\1\\" alt=\\"-\\" />',
  ),
);
?>

I am a Web Development Contractor, I do not work for UBBCentral. I have provided free User to User Support since the beginning of these support forums.
Do you need Forum Install or Upgrade Services?
Forums: A Gardeners Forum
UBB.threads: UBBWiki, UBB Styles, UBB.Sitemaps
Longtime Supporter & Resident Post-A-Holic
VNC Web Services: Code Modifications, Upgrades, Styling, Coding Services, Disaster Recovery, and more!