Updating multiple node fields
I guess my first question is how many nodes are you looking to update. If it's a relatively small amount, you should just use VBO (per the article you referenced). That is the easiest contributed module method of updating multiple nodes.

However, it is possible for you to create your own module (i.e. custom_node_update) and run the node_mass_update upon form submission (as recommended by the API documentation). This will be especially useful if you are updating a large number of nodes because it will batch it appropriately, however, you'll be required to write some custom code. 

Does this answer your question?