Using batchfile to setup environment for running .NET Process

Today I faced a problem that I wanted to use a third party library, which depends on all kind of environment settings. Since this library came with an accompanying batch file for setting up this environment, I would like to reuse this batch file. After much googling I could not find a satisfying solution for my problem and decided to go for my own. The resulting code is here

// Run 3 commands in a "batch":
//   setenv.bat: this will correctly setup the environment
//   CLS: Ths will clear the screen (effectively sends a formfeed (\f) to the StandardOutput stream)
//   SET: This will display the current environment variables (or send it to standard output
var processStartInfo = new ProcessStartInfo("cmd.exe")
                           {
                               Arguments = string.Format("/c {0} && CLS && SET", pathSetEnv),
                               RedirectStandardOutput = true,
                               CreateNoWindow = true,
                               UseShellExecute = false,
                           };
var process = Process.Start(processStartInfo);

// Wait until all commands have been processed
process.WaitForExit();

// Grab standard output
var standardOutput = process.StandardOutput.ReadToEnd();

// Grab all lines since last formfeed
var lastFormFeedIndex = standardOutput.LastIndexOf('\f');
var environmentSettings = standardOutput.Substring(
    lastFormFeedIndex).Split(new [] { Environment.NewLine }, 
    StringSplitOptions.RemoveEmptyEntries);

// Adjust the current Environment Variables with the ones grabbed
foreach (var environmentSetting in environmentSettings)
{
    SetEnvironmentVar(environmentSetting);
}

With the following helper for setting the environment:

[DllImport("msvcrt.dll")]
public static extern int _putenv(string varName);

private static void SetEnvironmentVar(string environmentSetting)
{
    // We can not use Environment.SetEnvironmentVariable(variable, value); 
    // The problem relates to an unbalanced environment string encoding (ANSI/UNICODE).  
    //
    // To prevent such errors, pair the getenv() call with a _putenv call to set  
    // the environment variables in C#. When using SetEnvironmentVariable() (from  
    // Kernel32.dll) pair it with a GetEnvironmentVariable in C++ and match your  
    // string encodings.  
    //  
    // So what uou need to do is replace your SetEnvironmentVariable call with ...  
    // [DllImport( "msvcrt.dll")]  
    // public static extern int _putenv( string varName);

    // Environment.SetEnvironmentVariable(variable, value);
    if (_putenv(environmentSetting) == -1)
    {
        throw new TcliWrapperException("Unable to set environment variable");
    }
}