Samurai's tactic will work. But if you are afraid of dogs, specifically this dog, it will know, and then it won't work.
I have done this with my Irish terriers. My first Irish just did NOT get it for awhile. She spent any number of minutes on her back over the years. My "roar" was to look her in the eye ONCE SHE WAS DOWN AND CONTROLLED and yell "YOU ARE NOT ALPHA!!!! I AM ALPHA!!!!!"
I did that so that if she started acting up later, that was a phrase I could use and head off rising unacceptable behavior. It worked.
However, if you don't know what you're doing with dogs, I'm not sure I'd recommend it. I've had dogs all my life and I've had terriers a long time, so I'm utterly comfortable with it.
(I have to tell a story as an aside: my oldest son was extraordinarly irritated by my middle son's outrageous behaviors in middle childhood. MS would just never know when to quit. OS was 12 years older than MS. So OS started doing those 'alpha sessions' on HIM. Guess what. It worked....! That is until MS grew up to be bigger than OS
)
Springmom