$("td:contains('Display emoticons in your post')").append("<br /><input type='checkbox' onclick='Dice_Is(this.checked)'> Enable Dice Roll?");

function Dice_Is(really){
if(really==true){
document.forms['posting'].onsubmit=function(){
document.forms['posting'].post.value+="\n\n\nYou rolled a: [b]"+Math.floor(Math.random()*10+1)+"[/b]!";
}
}
}