Displaying Date In Text Box

I want to display the date 19/06/2007 in this format.I want to validate the number entered in the textbox i.e for first digit of date it should not accept more than 3 (accept only 0,1,2,3). When the text length reaches 3 & 5 ie after date & month, by default this function should return slash ( / ) - this is to avoid typing / from keyboard.
I don't have any idea to do this.

I have added the function below, which I will be calling onkeypress event.

OnKeyPress="javascript:valNumber(this.value);"
function valNumber(value)
{

var x=value.length;
if(x==0 && (event.keyCode==48||event.keyCode==49||event.keyCode==50||event.keyCode==51))
event.returnValue=true;

else if(x==1 && (event.keyCode>47 && event.keyCode<58))
event.returnValue=true;

else if(x==2)
value = '/'

else
event.returnValue=false;
}