To add to what ~Svenler suggested, you may find that you’ll either A) need a good deal of space between your backdrop and the pair of lights if you want them pointed at one another at a 90º angle to the direction of your camera, in order to prevent light from spilling onto the backdrop; or B) need something like a pair of large foamcore sheets between the model and your camera if you choose to angle the lights forward, to prevent the light from spilling into your camera. I did a shoot like this recently, except that I had the model lit with an extra strobe in front. This is a view of my setup. Notice the two medium softboxes at the back are angled directly back towards the camera, but I had black foamcore sheets to flag them off.
Another option would be to use a grid on the two softboxes to help control the direction of the light. Then you could get away with having them angled slightly towards the camera without having to worry about lens flare.
Good looking setup! Space can be a problem because the studio in my friends school is quite small (original use is for promotional product photography). Extra strobe in front is also considered in this shoot. Thanks for the tips!
If space is at a premium, then your best bet would be to get four large sheets of black foam core (4 foot by 8 foot or so). You may need extra stands and clamps to hold them all, but I’ll let you figure that part out. Position the foam core sheets so that they provide baffles between the lights and the backdrop, and between the lights and the camera position. In effect, you’re creating a narrow hallway of light at a 90º angle to the camera. Your model should be halfway inside that hallway, but a little more towards the camera (you may have to do a couple of test shots to find the best position). That should prevent light from spilling onto the backdrop as well as from flaring into your camera.