Hooking and/or SubClassing. What are my options?

I'm writing an addin for the IDE which needs to know about changes of focus in the project window treeview. I first thought to subclass the window,but couldn't get it to work. I thought this was because you wre limited to subclassing in your own process. But a compiled addin would run in the same process as the IDE, would it not? And therefore subclassing should be possible?

If not, can I use Hooking? If I can, how do I do it? (I know less about hooking than I do about subclassing and I hardly know a thing about that!).

I can use SendMessage to get to text of the selected node in an external treeview, but I need to be informed when a new item is selected (TVN_SELCHANGED notify for example).

Please, Please, Please, Please, Please, Please, Please, Please, Please, Please, Please, Please, Please, Please, Please, Please, help.

Thank you.

Since no one was in a rush to help me out, I figured it out myself :p

The answers we all want to know are contained in this other thread.