Generally, pasteurization involves heating the beer until it reaches 170 degrees f to kill any microbes present in the liquid.
This typically isn't necessary in home brewing and can have adverse effects on your mead. The simplest way to preserve the flavors in your mead and halt the yeasts is to cold crash it. This means to chill your mead in a temperature controlled environment to cause it to slow down, go dormant and flocculate (settle) out of solution. The goal here isn't to pasteurize and kill the yeast, it's to slow the yeast down to a virtual stop.
For example, let's say you've been fermenting your mead for a few months, and you've taken some samples with a wine thief. You feel like your mead tastes pretty good and has some residual sweetness that you'd like to preserve. The best way to stop further fermentation is to take your mead and place it in a cold environment. Most brewers will use something like a freezer (either upright or chest/drop freezer) with an independent external temperature controller. These temperature controllers are more accurate and can dial in a specific temperature typically within a half a degree or greater accuracy. They are available for sale online or at your LHBS.
So, you put your mead into the freezer and then dial in a temperature of 35-40 degrees f or so, and you leave your mead in there for about a week. This is a low enough temperature to cause biological activity from the yeast to cease and fall out of solution nearly completely. You can then rack your mead off of the yeast cake at the bottom to a new vessel for bottling and cold storage.