Is it possible, get the Entry ID of the document(s) selected in Laserfiche client using a LF Client toolbar button (button: aplication external) and send the entry id how a parameter to the  aplication external (button)

What I am after is, to get the Entry ID of the document(s) selected in Laserfiche client. 

i'm using: 

string[] args = Environment.GetCommandLineArgs();

                for (int i = 0; i < args.Length - 1; i++)
                {
                    if (args[i] == "-SelectedEntries")
                        selectedEntries = args[i + 1];
                }

result: args[0] get the path of the application "c/:..../LFIntgDemo.exe"

I'm sure there's probably a simple method I've overlooked for doing this.

Any ideas?