To do this, go ahead and add a Blizzard Authenticator. There are two options. The first is to purchase a physical Authenticator, which will generate "unique, one-time use codes". This code, when paired with your account name and regular password, will protect your account. Even if you have been comprised by a keylogger, the code will not last long enough for very much vulnerability -- especially since you're logging in, yourself.
The second option is to download the mobile authenticator if you have an iPhone, iPod Touch, iPad, or Android phone. I personally use this on my iPhone and it functions just as well as the real option. Just be careful! If you're getting a new device, be sure to remove the authenticator from your account as you'll lose access. Also, don't lose your phone... though you probably have larger issues at this point.
In any case, if your account is hacked or you lose your authenticator, a call to Blizzard support will fix things as they can remove an auth after you prove you're the owner of your account.