Inside your customizing environment, create a new DGN library for your enhancements . A DGN library has the same file format as a DGN file, except that it has a different file extension. The recommended file extension is *.dgnlib. The procedure for creating a DGN library, either by creating a new file from the beginning or by copying an existing file and saving it with a new name, is the same as for any DGN file. The shared resources in a DGN library are created using MicroStation tools, the same way they are created in a DGN file. For details on this please read the chapter “Building DGN Libraries” in the MicroStation help file. For details on how to create tools, toolboxes and tasks you can start with the chapter “Customize dialog”.
If you have SITE DGNLibs added to your MS_DGNLIBLIST path, like $(_ustn_site)sisnet\*.dgnlib, copying the new created DGN library into your SITE folder will make it available to all project users. If you want the new DGN library to be available only to one user, extend the MS_DGNLIBLIST path in users .UCF file. A personal DGN library can contain only user interface modifications: customizations of tools, toolboxes, tasks, and menus.