Themes CAN be ported but its not necessarily an easy feat.
Essentially for vanilla android (no manufacturer UI like HTC sense, touchwiz, timescape etc) themes are /system/app/SystemUI apk and /system/framework/framework-res.apk
These are Rom components and are present in every GB android version onwards. These are what are Rom specific as its not just the images in there, it also references parts of code in the overall framework which was created for your specific phone. Replacing these files will prevent your phone from booting.
If its literally just images, you can open the framework-res from the theme and the Rom side-by-side and swap images. Same for sustemui. But if the theme includes elements that act differently, such as position changes, different dimensions etc, these are more than images and is a more advanced process.
But, you have a touchwiz theme (samsung UI) so I.doubt that can be ported to a phone without touchwiz. I bet the zip has more than the 2 files I previously mentioned. Your best bet would be an experienced themer with your device and ask for assistance. Still think its a long shot though