My bikeshop gave me these two mysterious little things along with recently purchased bike:
Miraculously I didn't throw them out (I am an avid and savage anti-hoarder, living in a very small house).
I now see why I need them. The first is optional, but the second one turns out to be absolutely indispensable as my other crank puller will not fit XTR cranks.
Replacement chainrings installed, ready for race. Woohoo!