I advise you to look in the solution application of Visual you can find it under the help menu. Thy have an example there that shows you how to enable/disable menus and it shows you how to put a mark in front of the menu. Like I Said I don't know if you can modify a menu at runtime unless you create it with an array at runtime. In the example they use the command SET SKIP TO. There's also some examples that add/remove menu items at runtime. If you would remove, change and add a menuitem you could change it's name from /name to name with a strtran.
Let me know if you found the solution in the solutions app else I'll look a bit further on the syntax etc...