what's a good technique for pasteurizing eggs?
The microwave is too harsh an environment for this.

If you have a sous vide circulator, you can also pasteurize in-shell at 135 F (57 C) for for 75 minutes according to Douglas Baldwin's A Practical Guide to Sous Vide Cooking.

To pasteurize on the stove in the shell takes some care. You must bring the water up to 140 - 150 F (60 - 65 C) for 3 to 5 minutes to pasteurize them. You must not exceed 150 or you will begin to cook the egg. If the eggs are in the water as you heat it then they will closely match the temperature of the surrounding water. Just make sure they aren't resting on the bottom of the pan. If you want to be extra careful you can leave them in longer, as long as you don't let them get too hot.

Alternatively, since you're using them in egg nog, you can combine the eggs with the milk and heat this slowly on the stove until it reaches a temperature or 140-150 F, maintaining for 3-5 minutes.