Add this code somewhere in WP or my theme's core so I don't need to add it to every page?

I had a programmer customize a plugin that allows the user to hit the spacebar and you can zoom into the image. Everything works right but you have add this bit of code to the HTML "Text" area of each page I want it to be active on. I would love it to be a more seamless integration if possible.

<div style="display: none;"> <link href="/wp-content/plugins/justified-image-grid/mega/css/custom-theme/jquery-ui-1.8.21.custom.css" rel="stylesheet" type="text/css" /> <link href="/wp-content/plugins/justified-image-grid/mega/css/lhp_miv.css" rel="stylesheet" type="text/css" /><script type="text/javascript" src="/wp-content/plugins/justified-image-grid/mega/js/jquery-1.7.2.min.js"></script><script type="text/javascript" src="/wp-content/plugins/justified-image-grid/mega/js/jquery-ui-1.8.21.custom.min.js"></script></div>

I have no clue what hook boxes do but I tried catalyst_hook_in_head and selected the appropriate custom page layout. Didn't work, but didn't expect it to be that easy.

Works correctly because the code is in the HTML of the page:
Does not work correctly, no code in HTML of the page:

Any suggestions?? Thank you!