Jaychad:
Im wanting to power my arduino via a battery pack. what kind of jack should be used, and is there any where on the arduino boards, uno and mega, that i can solder the wires to instead?
You can solder wires to the bottom of the board under the power input jack. There's some big solder joints there, perfect for adding a wire.
There's three pads. Check with a multimeter to see which pin is which. Two are connected to GND, one is connected the center pin of the jack.