We do it by putting the camera on a tripod and focusing on the computer
screen. We have a senior slide show which we composed and scanned all the
photos in Photoshop with titles then converted to slides. It is really easy
to do. To eliminate reflections you turn off all the lights. You must use a
shutter speed of 1/15 or slower so you don't get screen refresh lines in
your slide. Take a short test roll and find out your exposure for the screen
with some of your images. Use 100% for your screen images if using Photoshop
to reduce any jagginess of the image. You can eliminate all the tool bars
and background in Photoshop so your screen is clear and use a good monitor.
The quality is pretty good as we were putting the finished slides up on a 15
foot square screen.