A couple of ways you can do it.
System Preferences > Printer & Fax
you will see you printer listed in the left of the window.
Highlight it if it isn't already and above the picture of the device on the right side you will see a Print and Scan buttons
Click the Scan and then click open scanner and the scanning feature appears
Now the scanning window is opened.
You will now also see that on your Dock the printer/scanner device has appeared.
If you Control Click on it and select Options > Keep in Dock, when you close the scanner window the device will remain on the dock.
Each time you want to use it in the future, just click in the device in the dock and the print/scan window is loaded.
The other way is to use Image Capture.
Applications > Image Capture
When you load this Application, the scanner will be displayed under Devices, click on it and use the scanner.
Again, if you want to use it this way, with Image Capture open, you will see its icon in the dock and again you can Control click on it and Select Option > Keep in Dock, so when you want to use it, again all you need to do it click on the Image Capture icon.
I personally use Image Capture as I also use this Application for downloading my Photos from the iphone and digital camera.
Hope this helps.
