SetCommand(String)

SetCommand is the function which is made for send command to the plugin.
So if you would like to send a command to the plugin you need to use that
function with the plugin sample.
But in the first step you should find your plugin sample on your page,
the simplest way is the folowing:
embed=document.embeds[0];//it will point to the first plugin sample on the page
(There are several way to point your plugin sample) Than you can send your commands to the plugin sample.

Somehow like this:
embed.SetCommand(COMMANDSTRING);