we have fixed this on a client site so it works in ie8. its pretty simple, but there are a few changes needed:
1. rgba css doesn’t work in ie8 so we set some default background colours on the overlay div and .emodal class (black and white). for a full sultion you would need to detect browser in he script and add a hex rather than rgba in the js
2. you use the word “class” as variables in the defaults object. this is a reserved term, hence the expected identifier error in ie8 (other browsers just ignore it). we just changed that reference to “class_name” in the js file.
3. because of number 2 there is one part of the code (sorry forgot which part) that just passes all attributes to the object to be set. this had to be changed as otherwise it would a attribute of class_name=”classes” to the element.
with all that sorted it works in ie8, but obviously the css we have used is hard coded. for the plugin i would suggest browser detection and prevent the hex being converted to rgba for that browser.