keytool -exportcert -alias <yourAlias> -keystore <keystore path & file name> | openssl sha1 -binary | openssl base64
Keytool.exe is in your JDK/bin, you will need Java Development Kit (JDK) installed on your machine
debug.keystore is located in c:\users\<UserName>\.android if you've run eclipse. If not you'll have to search for it, no idea where Paul put it. The release keystore is wherever you put it.
If you use Eclipse to build you can also try this:
http://stackoverflow.com/questions/25028259/android-how-to-get-hash-key-from-created-keystore-for-foursquare
I can't help you beyond that as the command line has always worked for me.