How to install Synergy on sunray client ?

Sunray clients do not actually run programs. They are thin clients that run a unix shell just to start up the RDP client (which can be any OS the Sunray server is capable of ... Windows, Linux, Solaris, etc). It runs no other services. The applications are actually run on the Sunray server. In order for Synergy to work, it needs to be run on the system that will be using the keyboard/mouse/clipboard of the Synergy server.

I suppose if you can configure an RDP host to work as a Synergy client, you might get it to work. You would basically be setting up a virtual Windows PC (I am assuming Windows. Use the version of Synergy appropriate to your Sunray's OS) on the Sunray server to be a Synergy client to a real PC running the Synergy server. Technically it works, but not stably. In my testing, the mouse pointer disappears, and sometimes gets stuck in the RDP host's screen. You would be much better off to just access the Sunray client's session using an RDP client from the real PC to do the copy/paste work.