One fellow once described his technique for encouraging left handed shaking as being to pat the person on the cheek with the right hand while thrusting the the left hand into to person's belly to cause the preson to grab that hand - almost always with the left hand so that it could be grasped and shaken as he stepped back a little.

'Twas said he gave up the practice when the other guy grabbed him with both arms and planted a great big tonsilsuckin' kiss.

I lost contact, so don't know if he's improved on his method.

John