HI
try this
<cc1:TimeSelector ID="TimeSelector2" runat="server" Date="05/10/10 2:30:00 PM" MinuteIncrement="15" AllowSecondEditing="false" /> <cc1:TimeSelector ID="TimeSelector3" runat="server" EnableClock="true" />
<b>Validator Example, AllowSecondEditing set to false</b>:
<MKB:timeselector ID="TimeSelector3" runat="server" MinuteIncrement="15" /> <MKB:TimeSelectorAvailabilityValidator ID="TimeSelectorAvailabilityValidator1" runat="server" ControlToValidate="TimeSelector3" Display="Dynamic" ErrorMessage="That time is already taken!" />
<b>Validator Code Behind</b>:
List<DateTime> list = new List<DateTime>();
list.Add(DateTime.Now);
list.Add(DateTime.Now.AddSeconds(30));
list.Add(DateTime.Now.AddMinutes(30));
list.Add(DateTime.Now.AddHours(3));
TimeSelectorAvailabilityValidator1.AppointmentList = list; TimeSelectorAvailabilityValidator1.AppointmentLengthInMinutes = 90;
Screensot
OR
http://www.codeproject.com/KB/selection/cstimepicker/TimePicker_src.zip

refr the links
http://www.asp.net/community/control-gallery/Item.aspx?i=3221
http://www.codeproject.com/KB/selection/cstimepicker.aspx
hope it helps you...