You just have to get extremely lucky, LOL. If it were possible, I would've had Hopper move into my town eons ago...
Unfortunately for us, getting annoying neighbors to move out is easier said than done in this game; it just happens 'randomly', now... I once had my neighbor Ed, (really creepy horse villager BTW), ask to leave, but he ended up staying right after I told him to move! >_< It's like Nintindo is "trolling" us in a way...
But I still wish you best of luck; may both of us be reunited with our penguin friends!