Within a Run Script step, you can reference it just like that. If the code is in project/global script (View | Other Windows | Script Editor), use
dbFile = Application.ExpandMacrosAndScript("%PROJECT_DIR%") & "\myFile.db"
http://www.kinook.com/VisBuildPro/Manual/runscript.htm
http://www.kinook.com/VisBuildPro/Ma...ripteditor.htm