Sometimes, you may wish to run a batch file or command script that initializes several environment variables (for instance, vcvars32.bat or vsvars32.bat from Visual C++, setenv.bat from the DDK, or a custom batch file that initializes many environment variables) and make those environment variables available to other processes within a Visual Build project.
If a batch file is executed from a Run Program or Batch File action, the environment variables it creates will exist only for that step. To update variables for another step (process), use the
Command to run before main command field on the action's Advanced tab (this works for all actions that run programs, including Run Program, Batch File, Make VS.NET, Make Delphi, etc.). Enter the batch file to run in this field -- when the step is built, that batch file will be executed first, and any environment variables created or updated by the batch file will be inherited by the action's main command/process.
See here for more info:
http://www.kinook.com/VisBuildPro/Ma...dvancedtab.htm