I gave it a go, but no luck. I also had made sure that perl was in the correct PATH before. But changing to full path did not do the trick (if I did it right)
pp = "c:\\Perl64\\bin\\perl.exe"
pid = ipcBeginProcess(pp)
"Cannot create child process 'c:\\Perl64\\bin\\perl.exe '; Error code: 50\n"
The example with dir, was only to try an other command, which resultet in an other error code. I have tried to find information about these error codes, but no luck so far. But I didnt actually think about dir was inside cmd.exe, I tried with date as well, as this is used as example in the manual, gave same error code. (Error code: 2)