How much access do you have in the area?
This makes all the difference.
The drill and hammer method does work but you stand a very large chance of getting something detrimental into the engine.
Unless this is an emergency I would suggest trying other methods.
I like to use a few different punches. They usually have to be made to fit the job so plan on making them into dedicated tools.
Grind one punch to match the curve of the plug hole exactly. This punch should be about 3/8" wide at the most.
Using an angled approach hammer in a small portion of the plug edge until you can grab it with a small pair of vice grips...the needle nose style works great here.
Pry that plug out.
If the plug is installed with the flat side out then you will need a few more punches. The next punch is made to grip the edge of the plug. After hammering the edge in a bit with the curved punch insert the sharp punch and work it into the plug a bit. Next use it to pry the plug outward. The second step sometimes takes three or four sets of punching, prying, and resetting to get the plug out enough to grab it. Keep at it and you will get the plug out.
If that will not work I suggest calling 1-800-ACMETNT. They have some lovely fused devices that will completely eliminate all issues with this particular engine.