Sharepoint 2010: show "Add new item" or "Add new" for custom ListViewWebPart

First create a application page and copy below code. you can access this page like this.

http://serverma,e/_layouts/test.aspx

.CS Page
=======================================================

public partial class Test : LayoutsPageBase

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            try

            {

                SPSecurity.RunWithElevatedPrivileges(delegate()

                {

                    using (SPWeb oHomeWeb = new SPSite(SPContext.Current.Site.Url).OpenWeb())

                    {

                        oHomeWeb.AllowUnsafeUpdates = true;

                        SPList oWorkingDocumentsList = oHomeWeb.Lists["Announcements"];

                        SPView oCustomView = oWorkingDocumentsList.Views["All items"];

                        oCustomView.RowLimit = 5;

                        XsltListViewWebPart lvwpShowFiles = new XsltListViewWebPart();

                        lvwpShowFiles.ID = "wpListView";

                        lvwpShowFiles.Title = "Announcements using XsltListViewWebPart";

                        lvwpShowFiles.ChromeType = PartChromeType.TitleAndBorder;

                        lvwpShowFiles.AllowEdit = true;

                        lvwpShowFiles.AllowConnect = true;

                        lvwpShowFiles.ListName = oWorkingDocumentsList.ID.ToString("B").ToUpper();

                        lvwpShowFiles.ViewGuid = oCustomView.ID.ToString("B").ToUpper();

                        PropertyInfo nodeProp = oCustomView.GetType().GetProperty("Node", BindingFlags.NonPublic | BindingFlags.Instance);

                        XmlNode node = nodeProp.GetValue(oCustomView, null) as XmlNode;

                        XmlNode toolbarNode = node.SelectSingleNode("Toolbar");

                        if (toolbarNode != null)

                        {

                            if (!toolbarNode.Attributes["Type"].Value.Equals("Freeform"))

                            {

                                toolbarNode.Attributes["Type"].Value = "Freeform";

                            }

                        }

                        oCustomView.Update();

                        dvSummaryView.Controls.Add(lvwpShowFiles); //create div controls in a aspx page

                        oHomeWeb.AllowUnsafeUpdates = false;

                    }

                });

            }

            catch (Exception ex)

            {

                throw ex;

            }

        }

    }

.ASPX Page

==================================================================

<%@ Assembly Name="$SharePoint.Project.AssemblyFullName$" %>
 

<%@ Import Namespace="Microsoft.SharePoint.ApplicationPages" %>

<%@ Register Tagprefix="SharePoint" Namespace="Microsoft.SharePoint.WebControls" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

<%@ Register Tagprefix="Utilities" Namespace="Microsoft.SharePoint.Utilities" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

<%@ Register Tagprefix="asp" Namespace="System.Web.UI" Assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" %>

<%@ Import Namespace="Microsoft.SharePoint" %>

<%@ Assembly Name="Microsoft.Web.CommandUI, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Test.aspx.cs" Inherits="OPSSitePages.Layouts.OPS.Test" DynamicMasterPageFile="~masterurl/default.master" %>

<asp:Content ID="PageHead" ContentPlaceHolderID="PlaceHolderAdditionalPageHead" runat="server">

</asp:Content>

<asp:Content ID="Main" ContentPlaceHolderID="PlaceHolderMain" runat="server">

<div id="dvSummaryView" runat="server"></div>

</asp:Content>

<asp:Content ID="PageTitle" ContentPlaceHolderID="PlaceHolderPageTitle" runat="server">

Application Page

</asp:Content>

<asp:Content ID="PageTitleInTitleArea" ContentPlaceHolderID="PlaceHolderPageTitleInTitleArea" runat="server" >

My Application Page

</asp:Content>

Please refer below post as well
http://suryapulipati.blogspot.com/2011/08/sharepoint-2010-custom-listview-webpart.html