One way:
Option Explicit
Sub auto_open()
Dim myCMDBar As CommandBar
Dim myNewCtrl As CommandBarControl
Set myCMDBar = Application.CommandBars("formatting")
On Error Resume Next
myCMDBar.Controls("my New Item").Delete
On Error GoTo 0
Set myNewCtrl = Application.CommandBars("formatting").Controls.Add _
(Type:=msoControlButton, temporary:=True)
With myNewCtrl
.Caption = "my New Item"
.OnAction = ThisWorkbook.Name & "!" & "mynewitemmacro"
.Visible = True
.BeginGroup = True
.FaceId = 232
End With
End Sub
Sub auto_close()
On Error Resume Next
myCMDBar.Controls("my New Item").Delete
On Error GoTo 0
End Sub
Sub myNewItemMacro()
MsgBox "hi from my new item"
End Sub
If you're looking for nice icons:
John Walkenbach has a FaceId identifier program at:
http://j-walk.com/ss/excel/tips/tip67.htm
Jim Rech has one at:
http://www.oaltd.co.uk/MVP/MVPPage.asp#JimRech