You can make them with a number of different flours, I'm sure. If it says masa for corn tortillas, it should work. We've sometimes had to go searching far and wide in a 20 miles radius here in NJ, as it seems to often be sold out. The ones she's used are: Maseca "Masa Instantanea de Maiz", and Goya "Masarepa" "pre-cooked". These flours are precooked, which I think is an important point. After that, it's just a matter of making a mixture of water and flour, I think it's probably about equal parts by volume, and adding a little salt and oil. You form fist sized balls that have a consistency of fairly firm dough, so you can adjust, if my guess on the amount of water my daughter uses is wrong. I think she adds water a little at a time and waits until the dough feels right, so she probably doesn't know what amount of water she actually uses (she's in school, so I can't ask her right now). We then press them out by pushing the bottom of a bowl down on the ball, which we put inside a folded ziploc  bag, if that makes sense to you. Then they can be cooked any number of ways, but we like putting them on a fairly hot griddle and turning them a couple of times. They should separate in the middle, and then you can stuff them if you want. I guess we use them more like tortillas. We rarely put anything other than a little cheese on them. They are actually very flavorful without any stuffing or anything on them. I'm not absolutely sure of what defines an arepa, so if this isn't exactly what a Venezuelan would say is right, I'll stand corrected.

Susan:

 Haven't had these in a long time but the link below might help:

http://www.foodnetwork.com/food/recipes/recipe/0,1977,FOOD_9936_27484,00.html

Wayne

http://www.internationalrecipes.net/recipes/view.pl?2474

Your comments and links are greatly appreciated! 
SD Susan