For makecert, your startInfo.FileName
should be the complete path of makecert (or just makecert.exe if it's in standard path) then the Arguments
would be -sk server -sky exchange -pe -n CN=localhost -ir LocalMachine -is Root -ic MyCA.cer -sr LocalMachine -ss My MyAdHocTestCert.cer
now I'm bit unfamiliar with how certificate store works, but perhaps you'll need to set startInfo.WorkingDirectory
if you're referring the .cer files outside the certificate store