To run the mpi2nas.vbs macro:
The API script saves the interface files in a folder created within the current project folder. For example, My Documents\My AMI 20xx Projects\Project1\<study_name>_interface_files, where xxxx is the software release number and <study_name> is the name of the study you are exporting to NASTRAN.
Once the files are in that location, you can use them in NASTRAN. Refer to your NASTRAN manual for instructions on how to import them.