Project
|...Controls
    |...MyDateTimePicker.cs
    |...MyDateTimePicker.js

[assembly: System.Web.UI.WebResource("Project.Controls.MyDateTimePicker.js", "text/javascript")]

[DefaultProperty("ID")]
[ToolboxData("<{0}:MyDateTimePicker runat=server />")]
public class MyDateTimePicker : WebControl, IScriptControl
{

}

protected override void OnPreRender(EventArgs e)
{

    if (!this.DesignMode)
    {

        // Link the script up with the script manager
        ScriptManager scriptManager = ScriptManager.GetCurrent(this.Page);
        if (scriptManager != null)
        {
            scriptManager.RegisterScriptControl(this);
            scriptManager.RegisterScriptDescriptors(this);
            scriptManager.Scripts.Add(new ScriptReference(
                "Project.Controls.MyDateTimePicker.js", "Project"));
        }
        else
        {
            throw new ApplicationException("You must have a ScriptManager on the Page.");
        }

    }

    base.OnPreRender(e);

}

public virtual string TimeHourFormat {get;set;}
public virtual string TimeFormat {get;set;}

IEnumerable<ScriptDescriptor> IScriptControl.GetScriptDescriptors()
{
    ScriptControlDescriptor desc = new ScriptControlDescriptor("Project.MyDateTimePicker",
        this.ClientID);

    // Properties
    desc.AddProperty("timeHourFormat", this.TimeHourFormat);
    desc.AddProperty("timeFormat", this.TimeFormat);

    yield return desc;
}

IEnumerable<ScriptReference> IScriptControl.GetScriptReferences()
{
    ScriptReference reference = new ScriptReference();
    reference.Assembly = Assembly.GetAssembly(typeof(MyDateTimePicker)).FullName;
    reference.Name = "Project.MyDateTimePicker.js";
    yield return reference;
}

Type.registerNamespace('Project');

Project.MyDateTimePicker = function (element) {

    this._timeHourFormat = null;
    this._timeFormat = null;

    // Calling the base class constructor
    Project.MyDateTimePicker.initializeBase(this, [element]);

}

Project.MyDateTimePicker.prototype =
{

    initialize: function () {

        // Call the base initialize method
        Project.MyDateTimePicker.callBaseMethod(this, 'initialize');

        $(document).ready(
            // See, jQuery!
        );

    },

    dispose: function () {

        // Call the base class method
        Project.MyDateTimePicker.callBaseMethod(this, 'dispose');

    },


    //////////////////
    // Public Methods
    //////////////////

    // Hides the control from view
    doSomething: function (e) {

    },

    //////////////////
    // Properties
    //////////////////

    get_timeHourFormat: function () {
        return this._timeHourFormat;
    },
    set_timeHourFormat: function (value) {
        var e = Function._validateParams(arguments, [{ name: 'value', type: String}]);
        if (e) throw e;
        if (this._timeHourFormat != value) {
            this._timeHourFormat = value;
            this.raisePropertyChanged('timeHourFormat');
        }
    },

    get_timeFormat: function () {
        return this._timeFormat;
    },
    set_timeFormat: function (value) {
        var e = Function._validateParams(arguments, [{ name: 'value', type: String}]);
        if (e) throw e;
        if (this._timeFormat != value) {
            this._timeFormat = value;
            this.raisePropertyChanged('timeFormat');
        }
    }

}


Project.MyDateTimePicker.registerClass('Project.MyDateTimePicker', Sys.UI.Control);

if (typeof(Sys) != 'undefined')
{
    Sys.Application.notifyScriptLoaded();
}