CurrentProject.AllForms("какую-нибудь форму").Properties("{1187C6DF-2FFD-4fad-8138-A37C1AEABF39}") = "тест"

strtxt=CurrentProject.AllForms("какую-нибудь форму")....

Private Function SetFormProperty(FormName As String, strPropertyName As String, _
                                 strProperty As String) As Boolean
    ' Add custom properties to the AccessObjectProperties
    ' collection that is associated with an AccessObject object.
On Error GoTo  999 

    With CurrentProject.AllForms(FormName)
       If Nz(.Properties(strPropertyName)) <> strProperty Then
          .Properties(strPropertyName) = strProperty
       End If
    End With
    SetFormProperty = True

ExitHere:
    Exit Function

 999 :
    If Err.Number = acErrPropertyNotFound Then
       With CurrentProject.AllForms(FormName).Properties
           .Add strPropertyName, strProperty
       End With
       Resume
    Else
       SetFormProperty = False
       Resume ExitHere
    End If

End Function

затем
 call SetFormProperty("frm", "{1187C6DF-2FFD-4fad-8138-A37C1AEABF39}", "test")
затем прочтите.

Public Function NewEnum() As IUnknown
    Attribute NewEnum.VB_UserMemId = - 4 
    Set NewEnum = mcolControls.[_NewEnum]
End Function

Public Function Item(ByVal varID As Variant) As ClassResizeControl
    Attribute NewEnum.VB_UserMemId =  0 
    Set Item = mcolControls(varID)
End Function