How can shrimp be prepared to be Halal?
It cannot be "prepared" Halal, when meat is Halal. It is due to the slayer of the meat killing the animal in the name of Allah (swt). The process of shrimp being Halal or not is a complex topic in which the answer is bound to your madhab (school of thought if you are a Sunni Muslim).
What is the proper way to process shrimp to become Halal certified?
Again depending on the madhab, would determine the answer. However if you already are in a Muslim country that strongly supports a madhab that allows shrimp and or prawns just process shrimp normally, but make sure you process the shrimp without contaminating anything non-Halal such as bacon, etc.
We can IQF (individually quick frozen) or cook the shrimp, but they are dead from being out of the water before we process them organically, without any chemicals.
That is fine as to my knowledge (if you are following a madhab that allows eating shrimp), such as the Shafi'i, they declare everything from the sea to be Halal.
In Hanafi madhab, it is haram to eat shellfish (lobster, crab,
shrimp, oyster, etc.)
In Shafi'i and Hanbali, everything from the sea is halal.
In Maliki, everything but the eel is halal.
I cannot find each source for this, but know I read it some where. (Apologize for no citation.)
Much to my own confusion there is a Qur'anic verse that talks about sea food, in which allows us to eat sea food as it is Halal.
Lawful to you is the pursuit of water-game and its use for food,- for
the benefit of yourselves and those who travel; but forbidden is the
pursuit of land-game;- as long as ye are in the sacred precincts or in
pilgrim garb. And fear Allah, to Whom ye shall be gathered back.
I assume though that [6:145] still applies to sea food, so I would suggest keeping the treatment of the animal ethical.
Say: "I find not in the message received by me by inspiration any
(meat) forbidden to be eaten by one who wishes to eat it, unless it be
dead meat, or blood poured forth, or the flesh of swine,- for it is an
abomination - or, what is impious, (meat) on which a name has been
invoked, other than Allah's". But (even so), if a person is forced by
necessity, without wilful disobedience, nor transgressing due limits,-
thy Lord is Oft-forgiving, Most Merciful.