Mary, I wonder if using "flood" light bulbs positioned as Mike suggested would help to soften the effect and give some directional effect.

The backlighted portraits on my site were painted just as Mike described: position the subject between the camera and the sun and spot meter off the face. It does result in some flatness of form, however. It is a great way to paint an outdoor portrait with a feeling of sunlight, though. If you have a fair bit of direct sunlight actually shining on the face it will produce awful squinting and harsh shadow edges.

Mary, if you want the backlighted effect with some directionality to the remaining light on the face you could position them with a tree or wall right next to them, I suppose.

Thanks very much Michele for your pointers :)