Yes, you can modify the following code and attach it as a .js file in the Resources section of the in5 export dialog:
$(window).load(function(){
$('.viewer-option-btn').each(function(index,elem){
$elem = $(elem);
switch($elem.attr('title')){
case 'Go to Table of Contents': $elem.attr('title','new TOC name'); break;
case 'Toggle page thumbnails': $elem.attr('title','new thumbnail name'); break;
case 'Zoom in': $elem.attr('title','new zoom in name'); break;
case 'Zoom out': $elem.attr('title','new out name'); break;
case 'Toggle fullscreen': $elem.attr('title','new fullscreen name'); break;
case 'Download PDF version': $elem.attr('title','new pdf name'); break;
case 'Built with in5': $elem.attr('title','new in5 message'); break;
}
});
});
It will rewrite the title attribute(s), which is what is shown on rollover.