How to show glyph on indicator margin at given line number

Hi , I have new requirement of showing a glyph on indicator margin at the given line number . I had gone through following  sample  

https://msdn.microsoft.com/en-us/library/vstudio/ee361745(v=vs.110).aspx

but problem here is GetTags method of ToDoTagger class is automatically called on load or whenever we edit something in code . 

I am not able to understand how i can call it explicitly from the tool window code where user will provide a line number and i want the glyph should be drawn on that line number .

I don't want this GetTags method to be called implicitly at any point of time (on load and editing) . I just want this to be called whenever required or any other way i can have the glyph drawn on particular line number .

Thanks in advance .