Set password for OMD Site user to use with SFTP?

The question is how do I set the site user’s password using passwd if I don’t get the initial password, and in that same vein, how would I copy the privkey to another client If I can’t login directly to the user in the first place?

I tried copying it to /tmp/ and using chown to pull it using a different user, but that makes they key not work anymore obviously.