No keyhole? Lots of cars have a plastic cover that can be popped off to reveal a keyhole. Beyond that ...
I know nothing of it more than what Google tells me, and it told me a good idea. Jack up the left front and put it on jackstands. Crawl underneath with suitable jumper cables, locate the red (+12) cable to the starter motor and connect your red jumper cable to that and the black one to any suitable chassis ground. Hook up the other end of the jumper cables to a good 12V battery and you now have power to the vehicle, your remote should work.