Setting outlook item's user defined properties as readonly

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C#

Outlook

AddIn

Hi,
I have an Outlook add-on that stores a value in user properties part of an Outlook TaskItem. The saving part works well using the code below, but I want to be able to display this field in ToDoList as read-only. For the moment I am displaying it but the user can change the value.
I didn't find a way to set read-only. The properties mentioned on msdn doesn't seem to allow this MSDN

My code is:

if (task.UserProperties["TMSTaskID"] == null)
     {
                    task.UserProperties.Add("TMSTaskID", Outlook.OlUserPropertyType.olInteger, Type.Missing, Type.Missing);
                }
                task.UserProperties["TMSTaskID"].Value = _MyTask.TaskID;
                task.Save();

If anyone knows a solution or a workaround I'll really appreciate it.
Thank you
PS: I forgot to mention that I need to do this without custom forms