I recommend unbolting the hinge from the body, then drilling out the top Torx's to get the old hinge off. Don't try to spin the lower Torx's off. Put a ratchet on the nut and turn the nut. There will probably be a lot of body sealer on them so you'll have to dig them out.
Also, because they're behind the instrument panel, you will probably want to unbolt that so you can get back there. To get the instrument panel off you'll have o lower the windshield and unscrew all of the torx on the top of the instrument panel. Beware though, there could be a lot of rust there. Then remove the 3 torx per-side and you can swivel the whole instrument panel out enough to get back there. Otherwise, you can drill out the lower bolt heads and dig the rest out.
Then replace them with Allen head screws. Also keep in mind that there is no paint behind the hinge so there could be rust.