programmatically changing webkit-transformation values in animation rules

I have this stylesheet:

        @-webkit-keyframes run {
            0% {
                -webkit-transform: translate3d(0px, 0px, 0px);
            }            
            100% {
                -webkit-transform: translate3d(0px, 1620px, 0px);
            }
        }

Now, I would like to modify the value of 1620px depending on some parameters. Like this:

        @-webkit-keyframes run {
            0% {
                -webkit-transform: translate3d(0px, 0px, 0px);
            }            
            100% {
                -webkit-transform: translate3d(0px, height*i, 0px);
            }
        }

I would prefer to be able to use JavaScript and jQuery, though a pure CSS solution would be ok.

This is for an iPhone game that runs in it's mobile Apple Safari browser.