I ended up drilling and tapping the plug.
The most annoying part about the entire process was tracking down a 14mmx1.5 tap. Any industrial sort of tool place will have them, do-it-yourself sorts of stores probably won't.
Necessary tools & parts:
1/2" metal drill bit
metric socket set
M14x1.5 drain plug
5/8" crush washer
oil pan gasket
metric combination wrenches
3/8" torque wrench
1/2" torque wrench
Friend to help putting exhaust back on
You may or may not need to replace the gaskets for the exhaust - my exhaust gaskets didn't need replacing.
To get the oil pan off, you need to remove the exhaust. Removing the radiator will make life a little bit easier, but it isn't necessary (and I didn't do it) - it just makes it a bit harder to remove the right side exhaust. Removing the exhaust is easy. Two nuts on each pipe at the cylinder, one nut to loosen on the crossover under the oil pan, and the nut/bolt on each side holding the exhaust to the rear footpeg mount. It might take a little wiggling to get the right and left side apart.
Oil pan is 8mm bolts, and the screw holding the wire to the oil pressure switch. Remove all the bolts (keeping track of which bolt goes where is recommended, even though they're all the same size), and the oil pressure switch wire. It may take a few taps with a mallet to get the pan off. Once the pan is off, I used a razor to carefully remove the gasket bits from the case and oil pan.
A small pipe may come with the oil pan, if it does you'll need to put it back in before putting the oil pan back on. Wiggle under and look up, it's obvious where it goes and it'll stay there fairly well if the o-ring is in good shape (which it should be).
I got the drain hole lined up as best I could on the drill press, and clamped it upside-down to the press table. There isn't a lot of meat to the drain, so getting it centered is relatively important. Drilled the hole, and called it good. I also used the drill press and manually turned it to start the tap, just to be sure it got started straight. Once the tap is done, I tossed the oil pan in the bath/cleaner and made sure I got all the metal filings out. While it was there I also cleaned off the crap that had built up on the outside of the oil pan.
Putting the oil pan back on with the new gasket, I finger-tighted them first. Then did 8Nm (about 70 in.lbs) in an order which spread out pressure on the new gasket. If they were numbered clockwise 1 through 10, something like 1-6-3-8-2-7-5-10-4-9. I went around in the same order and finished them off to 12Nm (104 in.lbs) as my Haynes manual suggested. Re-attach the oil pressure switch wire, and put in the new oil plug and crush washer. Because the new 14mm plug has a different thread area (about 15% more) than the old 12mm plug, you probably don't need as much torque on the oil plug, but just for good measure I tightened it to 29Nm (22 ft.lbs) as suggested by the Haynes manual.
The exhaust is straightforward for putting back on, but having a second set of hands would have been very helpful. It would also have been a little easier if I had removed the radiator like Haynes told me to. I couldn't find ANY torque values for the exhaust in the manual, so I used 12Nm connecting to the cylinder (that's what it is for my yzf600), about the same for the crossover clamp, and 18Nm for the footpeg and exhaust mounts.
With everything re-assembled, fill with oil and away you go.