JQuery :: Cycle Slider - Add A Custom Function Script For Each Slide?

I'm using the jQuery Cycle plugin to slide some posts in wordpress, each with it's own image. As the slider should take the whole width of the screen but staying at 600px height I tried for all means to use the fit, width, height options in order to make that happen, with no success at all (apparently, it wont enlarge the images if needed).

So I wrote this little function and managed to make it work by adding it INTO the Cycle script itself (I mean the cycle js file):

$slides.each(function(){
var $slide = $(this);
var ratio = (opts.aspect === true) ? $slide.width()/$slide.height() : opts.aspect;

[Code]....

Now, I'm not sure (thinking surely not, right?) if I can add code directly into the Cycle js file, legally, I mean, without infringing the licence. Is there a way to make that function work for each slide (as a "for each slide independently do THIS...") from the jQuery call to the Cycle script, through some of the options?