Running X86 version of MSBuild programmatically

Question

I am currently running MSBuild programmatically using the following:

var pc = new ProjectCollection();
var buildProperties = new Dictionary<string, string>
    {
          {"Configuration", "Release"},
          {"Platform", "Any CPU"},
          {"OutputPath", _outputPath},
          {"EnableNuGetPackageRestore", "true"}
    };

var buildParameters = new BuildParameters(pc);
var buildRequest = new BuildRequestData(_solutionFilePath,
                       buildProperties,
                       "4.0", 
                       new[] { "Rebuild" }, 
                       null);

How do I force the above to run using the X86 version of the MSBuild runtime instead of the X64 version. The application this is running inside is a 64bit application.