One line to change password "WinSCP.com /key gen key.ppk /changepassphrase"

Hi all, I am trying to change the passphrase for a .ppk file.
I can change the password using CMD as Administrator by running the command "WinSCP.com /key gen key.ppk /changepassphrase", then entering the password twice.

I wish to do the above with a script, is there a way to set the password in one line?

I have tried a few things similar to below in a batch script but had no luck.

Can anyone point me in the right direction?

#Please not i had to split key gen as it is caught by the spam filter

You can use this (undocumented) syntax:
WinSCP.com /keygen key.ppk /passphrase=old /changepassphrase=new

Thank you very much Martin!

This was exactly what I needed to know.