Is it possible to charge the battery from the jump posts under the hood, or should the charger be hooked up directly to the battery?

 

Best connected directly to the battery posts. Did connect the negative terminal only. Cover it with a glove to avoid shorting out to ground and remember to not close the rear hatch. Put a folded towel over the hatch latch to avoid anyone closing the hatch on you.

 

It can be done under the hood as long if you know the right place to connect the negative cable; NOT the other lug on the fuse box, the marked nut on the strut tower.
Better at the battery to avoid confusion.. It is safest to charge a battery totally disconnected from the car with the caps off. Even "maintenance free." batteries have a removeable cap, just harder to see.