first but: it should be better if you can pick a hover effect image in the backend. i had to mod it and change entire code to make i work.
second but: the developers puts a hidden backlink in file
/modules/mod_jxtc_lightbox/mod_jxtc_lightbox.php with a display none style.
those buts give you a very poor rating from me.
P.S. Next time try at least not to use black hat SEO technics.
#1 This is free extension that is GPL and you are free to mod it etc, and you did so! Congrats - Please understand we have a support link on our website and we could have helped you and considered a hover image option for a future release. We welcome any questions and suggestions in our support system.
#2 Thank you for your feedback, we have removed the backlink (we no longer follow this practice) and will consider a hover image option for a future release. We wlecome any questions and sugestions in our support system.