Feature.EventReceiver.cs

public override void FeatureActivated(SPFeatureReceiverProperties properties)
{ 
    SPWeb web = properties.Feature.Parent as SPWeb;
    web.AllowUnsafeUpdates = true;
    try 
    {
        f(Microsoft.SharePoint.Publishing.PublishingWeb.IsPublishingWeb(web)) 
        {
            var publishingWeb = Microsoft.SharePoint.Publishing.PublishingWeb.GetPublishingWeb(web);
            foreach(SPListItem item in publishingWeb.PagesList.Items)
            {
                if(item.File.Name == "Home.aspx")
                {
                    publishingWeb.DefaultPage = item.File;
                    break;
                }
            }
            publishingWeb.Update();
        }
    } 
    finally 
    {
        web.AllowUnsafeUpdates = false;
    }
}