I missed your earlier reply. From your description, I think the following may be what you require.
Sub AddHour()    
    SetReminder 1
End Sub


Sub AddTwoHours()
    SetReminder 2
End Sub


Public Sub SetReminder(dHours As Double)
Dim olItem As Object
Dim dTime As Date
    Select Case TypeName(Application.ActiveWindow)
        Case "Explorer"
            Set olItem = ActiveExplorer.Selection.Item(1)
        Case "Inspector"
            Set olItem = ActiveInspector.currentItem
    End Select


    If TypeName(olItem) = "ContactItem" Then
        dTime = CDate(Now)
        dTime = DateAdd("h", dHours, dTime)
        With olItem
            .MarkAsTask olMarkNoDate
            .ReminderSet = True
            .ReminderTime = dTime
            .Save
        End With
    End If
    Set olItem = Nothing
End Sub