In the current treeview version you can drag and drop a node ON TOP of another node, to insert the dragged node before the one it has been dropped on.
With the current code snippet, you can drag and drop a node IN BETWEEN two nodes, and insert it between these two nodes. This scenario is more intuitive to users, this is why we provide the current Code Library project. Also, this functionality will probably make it into v6 of r.a.d.treeview.
Since, I was not able to understand your exact question, could you give us more details on what exactly you need to accomplish? From what I understand, you want to accomplish the first case above, which is actually build in the treeview. Let me know what I am missing.