Could you clarify what you mean? If you want to change them for every bootup, you can toss this into your AUTOEXEC.BAT: 
PATH=%PATH%;C:\h

[download]
If you're just talking about for the current program, you can modify %ENV. Or are you talking about modifying it for whoever runs your script?

In reply to Re: Updating window environment variables by Improv
in thread Updating Microsoft Windows (win32) environment variables by kirk123

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