Obviously you need a Merlin/Orion/Skywatcher remote head powered, turned on and connected to your computer with a modified serial cable (TTL converter).
There are 3 different packages available for download for : Linux, Mac and Windows.
The only difference is the start-up method with a supplied script file like .bat for Windows or .sh for Linux. The rest of the content is the same as Java is cross platform compatible.
You need the RXTX libarary installed the use Chronomotion. Get it from: http://rxtx.qbang.org/wiki/index.php/Download
First select a COM port (they are discovered automatically so must likely you will only have COM1 anyway) and press the "Connect" Button.
You should see Serial commands being sent and received in Terminal. This means everything connected properly and you can use all other buttons/commands.