I am asuming that you are talking about one of those where the photo it self is formed into that kind of bowl shape? (If just the glass in in the bowl shape and the photo is flat just take it out of the frame).
For the bowl shaped photos, take it out of the glass, set it up so that:
1. the light falling on it is even, no shadows, you might have to play with this.
2. Use a camera (film or digital) with a TELEPHOTO lens, back off till you get the thing framed, sharp, and shoot away with as many f stops as you can get, ie at least f11, 16 or 22 would be better. The reason for the distance is that the distortation between the part of the print that is closest to the camera and the part that is farther away will be minimized. You use the f stop to insure that the depth of field will hold so that the image is sharp from front to back. Remember that lenses may not be their sharpest at those f stops, so if you have an SLR, check the depth of field with your prevue button.
Also make sure that the print and the film plane are parallel with each other.
So you see it is not all that hard to do, one just has to make sure of the small details.
If you do not have a camera that will do this, see if a photo studio in your area will do it for you. We do things like this every so often for someone.
Hope this helps