extending SharePoint List - adding a button control to the toolbar

Question

I am creating a special Task List in SharePoint, I think that the best way to do that is through using SharePoint List Definition project in Visual Studio 2008, that's what I'm using.

I want to add a button control to the ViewToolbar of the list "AllItems" page, and to specify action when this button is clicked. all the articles that I found about List Definition project are about "adding a column to a list" So can anyone help me extending a List using List Definition Visual Studio 2008 project template - add a button.

Thanks