How can you change effect in Nivo Slider based off of previous or next slide keypress?

Question

I want to change the transition effect on Nivo Slider based off of which button was pressed. Any ideas of how to accomplish this?

Update To clarify

Answer 1

$('.nivo-prevNav').live('mouseover', function(){
     $('#slider img').attr("data-transition","sliceUpDown");
});

$('.nivo-nextNav').live('mouseover', function(){
     $('#slider img').attr("data-transition","sliceUpDownLeft");
});