Show tag selection pop-up in multi selection

[uscn2020]

I need to select/define tags to apply to a multiple selection of documents in Share (Alfresco 6.2). I have the multiple selection  working, invoking my web script where I fixed a tag for testing purposes. This is the relevat code in the YUI js file:

YAHOO.Bubbling.fire("registerAction", 
			{
				actionName: "onActionMyTags",
				fn: function tags_onActionMyTags(selectedNodes) {
					var nodeIDs = "";
					var tag = "";
                    var ii = 0;
                    for (var i=0, ii=selectedNodes.length ; i<ii ; i++){
        	        	nodeIDs = nodeIDs + "*" + selectedNodes[i].nodeRef.substring(24);
        	    	}
                    nodeIDs = nodeIDs.substring(1);
                    tag = "MYTAG";
					this.modules.actions.genericAction({
						success: {
							message: this.msg("msg.success")
						},
						failure: {
							message: this.msg("msg.failure")
						}
		                },
						webscript: {
							name: "mytagswebscript?nodeRef={nodeRef}&tag={tag}",
							stem: Alfresco.constants.PROXY_URI,
							method: Alfresco.util.Ajax.GET,
							params: {
                                nodeRef: nodeIDs,
                                tag: tag
                            }
						},
						config: {
							requestContentType: Alfresco.util.Ajax.JSON
						}
			})
		}
	});

I need to show the tag selection pop up that the user gets when he associates tags to individual documents in Share and put the selection in a tag array.

As a worst case solution I can settle for a pop up that shows a field where the user could type in tags (would separate with commas). I need for the field content to be available in the YUI js.

How is this done? Any pointers or links to a tutorial are appreciated.