Why not to add a button to the document library ribbon, and name it smth like "Create document by template"?
And on click, you can pop out SharePoint ModalDialog with your layouts page for asking some additional info (file name), or simply call your js function and create a document by template (most simple way is probably to use SPFile.CopyTo method to copy template from another document library, which you can hide if you wish).
You can either use standard SharePoint XML for adding ribbon button, or use Fluent Ribbon API (codeplex project, which simplifies ribbon creation).
You will need to add following code into your feature receiver:
var button = new ButtonDefinition()
Name = "CreateByTemplate",
Title = "Create by template",
Image = ImageLibrary.GetStandardImage(12, 9),
TemplateAlias = "o1"
var ribbonCustomAction = new RibbonCustomAction();
ribbonCustomAction.AddControl(button1, "Ribbon.Documents.New", 1);
ribbonCustomAction.Provision(ReceiverGuid, web, ListTypes.GenericLibrary);
For details, please visit Fluent Ribbon project documentation site, you will need section "Project features => RibbonCustomAction".