The first step was to loosen the rear wheel and slide the axle part way out so the adjusters were free. That created enough chain slack to pull the chain off the rear sprocket
I used a 10mm socket to remove the front sprocket cover's three bolts.
Then I grabbed a huge breaker bar and a 22mm socket. I stood on the rear brake and loosened the nut on the front sprocket. An impact wrench and 22mm impact socket would have been easier.
The old and new sprocket side by side. The stock is on the left and has a lot of rubber on it which reduces chain noise. I haven't noticed a lot of new chain noise with the new sprocket.
Install the new sprocket, put everything back together, and tighten it down. The last step was to re-adjust the chain.
The new sprocket definitely compensates for the gearing change by installing the D606s. Removing a tooth from the front is the same as adding three teeth to the rear. By adding the D606s I added about 1-1.5 teeth in the rear, so this change isn't as much as I had originally hoped. I do notice a difference, but it isn't as much as I expected; in all gears there is slightly more zip.
I am likely going to change the gearing to 13/47 when I can afford a new chain and sprocket kit. I will also keep the 12T around to swap to get really low gearing for trail riding.
The speedo is way off now with both the recent changes, so the next step is to borrow a GPS and get my SpeedoDRD installed.