Sorry. I misunderstood what you meant...

Which event do you want to fire? Treeview_NodeClick or Treeview_Click.

Regardless, you will have to call the event directly.

VB Code:
  1. Dim i As Integer
  2.     For i = 1 To frmmain.TreList.Nodes.Count
  3.         If frmmain.TreList.Nodes(i).Text = lstSearch.SelectedItem.Text Then
  4.             frmmain.TreList.Nodes(i).Selected = True
  5.             frmMain.TreList_NodeClick frmmain.TreList.Nodes(i)
  6.                 Exit For
  7.         End If
  8.     Next i

You will need to change the TreList_NodeClick procedure from Private to Public.