Question : How to make a password expire now?

Hi experts!

I know how to reset a password and force the user to change his password at next logon. This is NOT what I am looking for here.

For testing purposes I need to make a single domain user account's password expire at a given time without changing the whole password policy. Is there a way?
The net user /expire switch is not meant for passwords but for accounts.

The domain functional level is 2008 if of interest, so PSOs could be one solution. Any other solution?

Answer : How to make a password expire now?

PSOs are actually the only solution (unless you create a scheduled task that sets the password to "expired" on a certain date, but that's sort of "cheating", at least if you want to test the password policy).
The password expiration date is calculated dynamically based on the PwdLastSet AD attribute and maxPwdAge. For security reasons, only System is allowed to change PwdLastSet to an actual date; the only changes allowed when programmatically changing this attribute are 0 (password expired, user must change it) and -1 (password set today, user is not required to change it).