Disable the stock (?) alarm so I can safely reconnect the battery

[frankienap]

Hello all,
I have a 2008 Yaris Sedan. I'm the second owner and I believe the car has the stock (OEM) alarm system (not an aftermarket) installed. In the past when I've needed to unplug the battery to work on the car, I've also been hesitant because when reconnecting the battery the car alarm sounds immediately, which is pretty scary when you're working on a car and holding a battery terminal.
I'm looking to do some work on my car this weekend and what an answer to this question once and for all: how do you disable the stock alarm so that you can safely unplug and reattach your battery without the alarm going off?

I've searched the forums, but without luck. I even downloaded the "2008 Toyota Yaris - Theft deterrent system" manual from Toyota. Very confusing stuff. To deactivate the alarm, it says:

Unlock the doors or trunk using the key (vehicles without wireless
remote control) or wireless remote control door lock function
(vehicles with wireless remote control).
l Start the engine. (The alarm will be deactivated or stopped
after a few seconds.)

Then it later says

When the battery is disconnected
Be sure to deactivate the alarm system

Okay. But how do I deactivate the alarm when the battery is disconnected? The key FOB obviously doesn't work when the battery is disconnected.

Confused and looking for help.