I have an SA dog and I generally do not agree with crating a fearful dog. I can't tell you how important alone training is. Here's what you do:
Buy a Kong and stuff it with oh-so-yummy goodies. Freeze it or refridgerate it overnight.
The next day, take the now frozen or very cold Kong and place it on your dog's bed.
Turn on the TV or radio.
Close off all unnecessary rooms. For example, my dogs are only allowed in the living room when I'm gone. Every other room is closed off.
Close all windows and try to block all views of the outside world.
If you want, you can plug in your DAP Diffuser now or drop 4 drops of Rescue Remedy onto your dog's tongue. This step is optional.
Finally, leave the house nonchalantly and do NOT make a scene. Just pretend you're going out to get the mail. At first, you leave for 5 minutes. Then, after a few days, you leave for a period of 10 minutes. Then, after another week, 20 minutes. Then 30 minutes and so on. Do these "little leavings" periodically. I recommend doing this at least twice a day. This is also why I recommend buying two or so Kongs so you have them ready whenever you want to leave. It's very easy. Say you're watching a TV program. The commercial comes on. Take a stuffed Kong out and put it on your dog's bed. Leave for 5 minutes, come back with the same coolness and calm, and take the Kong away. Try to come back like nothing happened. Coming or going, don't make a scene. Good Luck and I hope your dog overcomes his/her SA.