To load a Macro in Microstation by default, complete the following steps:
Find the MDL called runmacro.ma and place it in the .../mdlsys/asneeded/ folder.
While in a FWP PDS model define the variable: "MS_DGNAPPS = runmacro" under WORKSPACE>CONFIGURATION
While in a FWP PDS model define the variable: "MS_DGNMACROS=Unit1ACS.bas" This is the name of the Macro we created above.
Now every time you enter a model your Macro will load.
This example is very basic and provides the user with the ability to load a single ACS base on a yes or no button response. It is possible to create a dialog box with a list of Auxiliary Coordinate systems from which to choose. See the MicroStation Help file "BASIC Editor" for some information on this topic.