Hi Amanda,
I would suggest you first mow down what is there if that hasn't been done already.* Then you could use either a radiant heat weeder or a flame weeder.* If using a flame weeder, DO NOT BURN POISON IVY!!!!
http://www.pesticide.org/radiant.html
http://www.pesticide.org/pubs/alts/pdf/flameweeding.pdf
http://attra.ncat.org/attra-pub/weed.html#top
You might find this helpful on how to use a flame weeder.
http://www.flameengineering.com/Flame_Weeding.html
You should be able to rent a flame weeder, but you would have to purchase your own propane tank.
Newt
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.