Thanks i figured i would have to go the JS route, for future searches here is what i've done.
on the Form added the following snippet to the script section.
Then used keyup and keydown events on the textbox to call the function.
onkeydown= "limitText(this.form.textbox,this.form.countdown,1000);"
onkeyup="limitText(this.form.textbox,this.form.countdown,1000);"
Added another textbox ID'd as countdown to decrement the count (visually).
function limitText(limitField, limitCount, limitNum)
{
if (limitField.value.length > limitNum)
{
limitField.value = limitField.value.substring(0, limitNum);
}
else
{
limitCount.value = limitNum - limitField.value.length;
}
}