Help with Lock 10 - Terms of Service

I need some help with applying validation for Custom AD button and Terms of Service. Please see screenshot:

![alt text][1]

Any clue how I can prevent users from sign up using custom button if they haven’t accepted terms?

My initial reaction would be that it is not supported, however, can you share a code snippet of how you configured Lock so that any analysis I do is based on your actual exact usage.

It is completely based on this article: