MSA14 install in grommet hole?

Not finding any documentation or assistance, I solved this on my own, even for a grommet hole slightly smaller than 2 inches in diameter.

After studying the downward extension below the base plate, I simply removed one plastic piece held in place by 3 small screws. (This piece would have been left in place for a "2.4-inch" hole.) Then I inserted the extension through my grommet hole, starting atop the desk, and it fit snugly but perfectly. I proceeded with normal installation of the large screw that snugs up to the bottom of the desktop. Then I reattached the plastic piece, also under the level of the desktop, which is unnecessary but provides somewhat helpful cable routing under the desk. In this position, only two of the three small screws could be fit, but that was adequate.

The product design also left room for my cables to run through the grommet hole in a gap next to the back edge of the base. If you're smart, you'll route those HDMI/VGA lines, plus power cord, and optional audio cables (for a monitor with speakers) before you slide the base into the hole and you will not have to restart.