I'm not sure what a tang is (other than that stuff the astronauts drink) but I put a needle or a toothpick or matchstick over the bridge between the holes in the button--whether sewing by hand or machine--to allow enough slack for a shank.
I've about given up on using the machine for buttons because of the problems mentioned here. Maybe there is a button sewing foot for my Viking (I've never looked) but I've dinged a few buttons and broken a needle when things have left their place without my permission.
This is one of those threads that makes this group useful to me. I had not thought of the use of an adhesive to keep the button in place and now that I have some nail polish on hand, maybe I can remember to use it on the buttons.
Max