Hi, welcome to Just Answer!. This is Ed.
Yes, the battery is in the trunk and you'll need to get in there to jump start the car. These vehicles don't accept a jump very well from under the hood when the battery is in an advanced state of dead, but will usually fire up when a direct connection to the battery is made. You'll need to have a power source to open the trunk from the button (or with your remote) of course, so that means you'll need to use jumper cables under the hood first just to energize the electrical system enough to pop the trunk. Alternately, you may lower the left rear seatback to gain access to the trunk, where you can pull the inside release handle located at the latch. It's a glow-in-the-dark plastic handle, but it's a bit of a stretch to reach.
Now, with the trunk open, make your jump start connections. The engine might start right away from this point, but the engine won't stay running until the battery begins soaking up charge; it'll just falter and die when the cables come off, despite the fact that your charging system will be working. It's just nature of the beast. The battery won't be accepting a charge immediately because it's been dead so long, so your electrical system voltage will be "choppy" from alternator output. Batteries serve a dual purpose -- they store energy for the future AND they soak up the rough alternator output ripple, smoothing the electrical system's voltage characteristics considerably. It's the ripple that the engine controller dislikes so much, confusing it and causing bad decisions to be made.
My feeling is that you'll need to charge your battery for at least a few hours to get it back to operating condition, so if time permits, just install a charger under the hood now. Charging works well from the jump start terminals, but ironically, jump starting does not. Give the battery some time and once it will start from battery power alone, you're good to go.