I haven't done it, but look under the dash on the passenger side. Since these are global cars, there are often unused holes (plugged up) because of the steering wheel being located on the opposite side in other countries. Even my 80s era Grand Wagoneer has unused holes in the firewall because of this.
I don't blame you. I'd be hesitant to drill new holes, too!!
I'm guessing you don't have a VR6, because those have the batteries in the trunk. :- )