How To Add A Back Slash To The TextBox For Date Format

function ValidateDate(txt, keyCode)
        {
            if(keyCode==16)
                isShift = false;
            var val=txt.value;
            var lblmesg = document.getElementById("<%=lblMesg.ClientID%>") ;
            if(val.length == 10)
            {
                var splits = val.split("/");
                var dt = new Date(splits[1] + "/" + splits[0] + "/" + splits[2]);

                //Validation for Dates
                if(dt.getDate()==splits[0] && dt.getMonth()+1==splits[1] && dt.getFullYear()==splits[2])
                {
                    lblmesg.style.color="green";
                    lblmesg.innerHTML = "Valid Date";
                }
                else
                {
                    lblmesg.style.color="red";
                    lblmesg.innerHTML = "InValid Date";
                    return;
                } 

                //Range Validation
                if(txt.id.indexOf("txtRange") != -1)
                    RangeValidation(dt);

                //BirthDate Validation
                if(txt.id.indexOf("txtBirthDate") != -1)                
                    BirthDateValidation(dt)
            }
            else if(val.length < 10)
            {
                lblmesg.style.color="blue";
                lblmesg.innerHTML = "Required dd/mm/yy format. Slashes will come up automatically.";
            }
}

 <asp:TextBox ID="txtValidate" runat="server" MaxLength = "10" onkeyup = "ValidateDate(this, event.keyCode)" onkeydown = "return DateFormat(this, event.keyCode)"></asp:TextBox> 

I want to include a slash within a TextBox for typing a Date.. I don't want it to generate a slash while typing...it should be static when the page is loaded.... Is it possible to do that without using AjaxToolkit ???