In essence you want to forbid a standard paste and possibly replace it by a paste special / values
You could trap the Paste function and assign a Message telling the user to use Paste Special / Values, like in
....
' place this in any suitable event trigger like
Application.CommandBars("Edit").Controls("Paste").OnAction = "TrappedPaste"
....
Sub TrappedPaste()
MsgBox "Your Paste is performed as PasteSpecialValues", vbOKOnly, "Paste"
' ok, now silently do a PasteSpecial/Values
On Error GoTo TryExcel
' try to paste text
ActiveSheet.PasteSpecial Format:="Text", Link:=False, DisplayAsIcon:=False
Exit Sub
TryExcel:
On Error GoTo DoesntWork
Selection.PasteSpecial xlPasteValues
Exit Sub
DoesntWork:
MsgBox "Sorry - wrong format for pasting", vbExclamation + vbOKOnly, "Paste Problem"
End Sub
Carefull ... this doesn't work in all languages, so for international applications we need to be more subtile
If ExistControl("Edit", 22) Then Application.CommandBars("Edit").FindControl(ID:=22).OnAction = "TrappedPaste"
And there are more places in the application where the user could get a "Paste" from, you need to trap them all.
I can elaborate further if you like the approach.