..Starting with katate tori hansha, step hantai tenkan and use your cross hand to break the grip like you are about to do an ikkyo. As you start to turn uke's arm over, use the same side hand to lock your thumb underneath uke's thumb. Move directly in to uke and spin your arm underneath the uke's elbow so you are standing side by side, with uke's elbow locked against your rib, and just lean both your hands on the back of uke's hand and pull back. The lock is solid and puts you in a good escort position if you just want to walk someone out the door...
Does it look similar to this at the end)?
Pretty sure we call it Renko Ho, or Gooseneck comealong (although I think it actually means "arresting technique"). The application would be like you would fake a "hammer lock" from the side/rear. Uke, and most people will pull their arm out and you just scoop it up, right into Renko Ho. Am I getting it?