You mention you are using a custom module. Is that a module build with the Dynamic Module Builder, or a real custom module as in a separate VS project?
In the first case you could add a new field to the module which would hold your hyperlink. Then inside the template you should change the markup to add a link.
In case of the separate custom module, you should be able to also add a new field to the model and make it available through the UI. This can all be done within code.