You can use the undocumented:
Application.SaveAsText acModule, "module1", "module1x.bas"
Application.LoadFromText acModule, "module1y", "module1x.bas"
Or you can simply save and load manually with right-click on the module name in the code window.
Finally, you can reference an Access application in the same way as any other reference, and then use the code. The file type *.mda was the library type. As far as I know, from 2007, you can create an *.accda library type.