I haven't found it easy to add to an already bound BIA project. The BIA seems to have been designed to work on completed projects, not half finished ones. As javagirl984 has already mentioned you could use the spiral punch to add pages as you go.
A couple of other suggestions:
1. Add lots of spare pages to your BIA book so you can add techniques into the book as you go without having to undo & rebind the book.
2. Use your BIA to make the holes and use the metal rings which you can open and close at anytime to bind the project instead of the Owire until such time as your project book is completely finished.
3. Use a 2 or 3 ring folder to store your techniques instead of permanently binding it with Owire.
I've personally used the last option for my technique file as I find it easy to organise & move pages around as my technique file grows.
HTH