You can scan using the button on your scanner.
Make sure that Epson Scan 2 is installed on your computer and the scanner is connected to your computer correctly.
When Document Capture Pro (Windows) or Document Capture (Mac OS) is installed on your computer, you can assign the job to a button on the scanner and run the job by pressing it.
Place the original.
Press the 
button.
See the Document Capture Pro (Windows) or Document Capture (Mac OS) help for details on button assignments.