Treeview moving from ADO.net to Entity Framework

Hi,
I have a treeview which I have working perfectly in VS 2008 using ADO but now I am writing the app again using VS 2012 and Entity Framework and could really do with some help changing it.  The code I use to populate the tree follows.

 public static DataSet GetEmployeeHiearchicalInfo()
        {
            DataSet ds = new DataSet();

            SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["RosConn"].ConnectionString);

            try
            {

                SqlCommand cmd = new SqlCommand();
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.CommandText = "Tree_Hierarchy";
                cmd.Connection = conn;
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                da.Fill(ds);
            }
            catch (SqlException)
            {
                throw;
            }
            finally
            {

            }
            return ds;
        }

        public void PopulateTree(DataRow dataRow, JsTreeNode jsTNode, DataTable tableNodes)
        {

            jsTNode.children = new List<JsTreeNode>();
            foreach (DataRow dr in tableNodes.Rows)
            {

                if (dr != null)
                {
                    if (Convert.ToInt32(dr["level"]) == Convert.ToInt32(dataRow["level"]) + 1
                    && Convert.ToInt32(dr["MangP_ID"]) == Convert.ToInt32(dataRow["Person_ID"])
                    )
                    {

                        JsTreeNode cnode = new JsTreeNode();
                        cnode.attr = new Attributes();
                        cnode.attr.id = Convert.ToString(dr["Person_ID"]);
                        //cnode.attributes.rel = "folder" + Convert.ToString(dr["Person_ID"]);
                        cnode.data = new Data();
                        cnode.data.title = Convert.ToString(dr["Name"]);
                        cnode.data.icon = null;
                        cnode.state = "leaf";



                        cnode.attr.mdata = "{ draggable : false, max_children : 100, max_depth : 100 }";

                        jsTNode.children.Add(cnode);


                        PopulateTree(dr, cnode, tableNodes);

                    }
                }
            }
        }

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Then this is in the Controller
   

public JsonResult GetEmployeeInfo()
        {
            DataSet dsNodes = RosterRepository.GetEmployeeHiearchicalInfo();
            DataTable tableNodes = dsNodes.Tables[0];
            DataRow parentDr = tableNodes.Rows[0];

            JsTreeNode rootNode = new JsTreeNode();
            rootNode.attr = new Attributes();
            rootNode.attr.id = Convert.ToString(parentDr["Person_ID"]);
            rootNode.attr.rel = "root" + Convert.ToString(parentDr["Person_ID"]);
            rootNode.data = new Data();
            rootNode.data.title = Convert.ToString(parentDr["Name"]);

            rootNode.attr.mdata = "{ icon :null : false, max_children : 100, max_depth : 100 }";

            rr.PopulateTree(parentDr, rootNode, tableNodes);



            return Json(rootNode, JsonRequestBehavior.AllowGet);
        }

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How can I convert this to use EF
Thank you for any help.