Listo, aquí el niño
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server" />
<div>
<asp:TextBox ID="myTextBox" runat="server" Width="283px"></asp:TextBox>
<div style="z-index: 101; left: 311px; width: 225px; position: absolute; top: 30px;
height: 37px">
<asp:TextBox ID="txtrecibe" runat="server" Width="211px"></asp:TextBox></div>
<cc1:AutoCompleteExtender ID="AutoCompleteExtender1" runat="server"
targetcontrolid="myTextBox"
servicepath="comple.asmx"
minimumprefixlength="1"
servicemethod="ObtListaIdentificacion"
completioninterval="250"
enablecaching="true"
OnClientItemSelected="GetCode"
completionsetcount="10">
</cc1:AutoCompleteExtender>
</div>
</form>
function GetCode(source, eventArgs ){
var textval=eventArgs.get_text();
var temp = new Array();
temp = textval.split('-');
//alert(textval);
var temp1=new Array();
temp1=temp[0].split(':');
document.form1.txtrecibe.value = temp1
temp1=temp[1].split(':');
document.form1.myTextBox.value = temp1
}
</script>
Lo que espero que esto me funcione tanto en firefox,googlechrome