I forgot to mention that I finally figured this out in case anyone ever needs to do this. Here's the code:
Public Sub CreateTempMenu()
'Declare Variables
Dim cbpop As CommandBarControl
Dim cbctl As CommandBarControl
Dim cbsub As CommandBarControl
'Create a Popup Control on the Main Menu Bar
Set cbpop = Application.CommandBars("Worksheet Menu Bar"). _
Controls.Add(Type:=msoControlPopup, Temporary:=True)
cbpop.Caption = "Temp Menu"
cbpop.Visible = True
'Add a Button Control Menu Item
Set cbctl = cbpop.Controls.Add(Type:=msoControlButton)
cbctl.Visible = True
'Next is Required for Caption
cbctl.Style = msoButtonCaption
cbctl.Caption = "Hello!"
'Action to Perform (place custom macro, function, sub, etc. in the quotes)
cbctl.OnAction = "someMacroOrFunctionOrSub"
End Sub