...
To run arbitrary commands on facet-srv01:
ssh -t USER@rhel6-64USER@centos7.slac.stanford.edu ssh -t USER@mcclogin ssh -t fphysics@facet-srv01 COMMAND
...
To transfer files from facet-srv01 to your local machine (leaves a copy on RHEL):
ssh -t USER@rhel6-64USER@centos7.slac.stanford.edu -t ssh USER@mcclogin “scp fphysics@facet-srv01:PATHTOFILE ~/transferStaging”; rsync -rP USER@$rhel6-64.slac.stanford.edu:~/transferStaging ~/transfer
...