How to pass parameters to plugin?

Hi all.

I am newbie of this wonderful text editor.
I tried creating new combobox with custom items and it's ok, but now i would like to customize items on base of a value read from querystring.
How can I do?
Thanks so much.

This is my code:

CKEDITOR.plugins.add('_bsvars',
{
    requires: ['richcombo'], //, 'styles' ],
    init: function (editor) {
        var config = editor.config,
         lang = editor.lang.format;
 
        var tags = []; //new Array();
        //this.add('value', 'drop_text', 'drop_label');
        tags[0] = ["{VAR1}", "VAR1", "VAR1"];
        tags[1] = ["{VAR2}", "VAR2", "VAR2"];
        tags[2] = ["{VAR3}", "VAR3", "VAR3"];
        tags[3] = ["{VAR4}", "VAR4", "VAR4"];
        tags[4] = ["{VAR5}", "VAR5", "VAR5"];
        tags[5] = ["{VAR6}", "VAR6", "VAR6"];
 
        // Create style objects for all defined styles.
        editor.ui.addRichCombo('_bsvars',
         {
             label: "Vars",
             title: "Vars",
             voiceLabel: "Vars",
             className: 'cke_format',
             //width: '200',  ??
             multiSelect: false,
             panel:
            {
                css: [config.contentsCss, CKEDITOR.getUrl(editor.skinPath + 'editor.css')],
                voiceLabel: lang.panelVoiceLabel
            },
 
             init: function () {
                 this.startGroup("List vars");
                 //this.add('value', 'drop_text', 'drop_label');
                 for (var this_tag in tags) {
                     this.add(tags[this_tag][0], tags[this_tag][1], tags[this_tag][2]);
                 }
             },
 
             onClick: function (value) {
                 editor.focus();
                 editor.fire('saveSnapshot');
                 editor.insertHtml(value);
                 editor.fire('saveSnapshot');
             }
         });
    }
});