How do you beat screaming mantis in Metal Gear Solid 4

From gamefaqs.com:

6. Screaming Mantis
====================================================
Recommended Weaponry (Lethal/Non-Lethal) - Assault Rifle, Mantis Doll (to
win)

This fight is extremely nostalgic to Psycho Mantis, and you will soon
find out why. You must protect yourself, as well as Meryl's own life
from Mantis' control.

Begin the fight by immediately injecting yourself with the syringe,
the actual fight will begin once you do that. If you look carefully,
you will notice two dolls to the left and right of Mantis. A Psycho
Mantis doll and a The Sorrow doll. You must shoot these, not Mantis
herself. Be careful of the floating FROG corpses, they can shoot you
or stab you if you get too close. Once you shoot either doll a few
times, Mantis will begin to manipulate Meryl more and have her attack
you.

Take cover behind one of the pillars at the top of the stairs, and
Meryl will leap over to you. Grab her using a CQC attack (remember
only handguns, knives or unarmed for a grab), make sure the syringe
is equipped, and then press the action button when she is grabbed to
inject her with the syringe. Basically this is the exact same thing
you did to Vamp. It will instantly knock her out.

Once Meryl is knocked out, continue to fire on Mantis' dolls. After
another few more hits, Mantis will raise Meryl once again, and put
the gun to her head this time. Quickly go down to the center of the
battlefield and grab Meryl in another CQC hold and inject her again
with the syringe. The FROGS corpses will most likely be near you and
will attempt to stop you. Keep trying to hit her with the syringe if
they land a hit on you.

Once you deal with Meryl again, you will finally be able to kill
Mantis freely. Continue to work on whatever doll you were shooting at
the time, you will notice it gradually fall from her side. After
about 10 hits or so it will fall from her side and fall to the ground
nearby. Quickly run to where the doll fell and pick it up before she
does herself.

Repeat this for the second doll. Be careful of her warping and slash
attack, she will scream "SNAAAAAKE" before she warps to you, giving
you plenty of time to run away. Once the second doll falls, you can
now kill Mantis. Equip the Mantis doll and fire off the projectile at her.
If it lands, you will be able to string her up like she did to the others.
Hold L1 and keep moving the Sixaxis back and forth between you and the screen,
this will shake her and inflict damage to her. You can kill her in one go
with this, quickly ending the fight. Note that both her stamina and health
gauge will deplete together.

*To end this fight quickly you only need to bring down the Mantis doll and
use it against her. The Sorrow doll is not needed to win, however if it is
your first time playing shoot both dolls so you can acquire both for future
playthroughs.

You know the drill now, either tranq or lethal kill Screaming Beauty
to win.