The hand-crank is self stowing under the cover. It engages the same mechanism as the electric motor. First pull and deployment of the hand crank disengages the motor and engages the hand crank. Because of the electric motor gearing and speed it takes a lot of turns to get the gear fully extended.
Hand-crank is slightly off aircraft centerline, in the floor and more towards the rear of the Passenger seat. Raising the cover and extending the handle, if I remember correctly, engages the system.
I took a lot of checkrides in the B-58 and manual gear extension always required extended holding patterns because you have to lean way over and reach behind the other seat to reach the handle when you to engage this system. You cannot accurately fly an approach and attempt to extend the gear at the same time. Go into holding, extend the gear and then complete the approach.
Hope this helps.