Did King James have any words put into the book of Deuteronomy in the translation of the Bible?

The question at the end of the body of the question asks:

Did King James ever tell those translating the Bible to include anything that was not in the original Hebrew OT or the Greek NT?

The King James Bible involved a huge amount of work by very learned men with input and comment from very many others. Also there were other translations available. King James was never in a position to command the scholars to add things into the Bible that plainly were not there. Any attempt to do so would have been vigorously resisted, and certainly exposed.

The main heading to the question is more subtle.

Did King James (VI and I) have any words put into .... the Bible?

Here the answer, to a certain extent, is yes. Instructions were issued to the translators in the name of King James (though actually sent by the Archbishop of Canterbury after consultation). These specified certain principles to be used in the translation, as necessary for consistency. They include.

3 The old ecclesiastical words to be kept, as the word church, not to be translated congregation.

4 When any word hath divers significations, that to be kept which hath been most commonly used by the most eminent fathers, being agreeable to the propriety of the place and the analogies of faith.

These two rules encouraged the use of familiar words, to assist the people to understand. Rule three gives an example. The Greek word ecclesia was, and is, sometimes translated congregation and sometimes church. Another example is whether to say overseer or bishop. The underlying Greek terms were originally common words not having a particularly Christian meaning but which came to be used as technical terms within Christianity. Translations still differ today as to in what way St Paul was using them.

Deuteronomy 18 v10 uses the word "witch" in the KJV. The near-contemporary Douay-Rheims (Catholic) Bible says "wizard". The Geneva Bible and the Bishops Bible and Tyndale all refer to one who "uses witchcraft" and, as @Lesley points out the modern NIV has "engages in witchcraft".

So the KJV is unusual in using the term "witch".

But, isn't a witch and a person who engages in witchcraft just the same thing? OP refers to "pagans or followers of the dark arts". Maybe, maybe not.

King James, and his contemporaries, understanding of a witch was as someone who had formally renounced her, or his, baptism and had made a formal and solemn pact to serve the devil. That is how the readers and hearers would understand the word "witch". This is different in meaning from someone who merely uses witchcraft. Whether or not there is a difference in practice, is another matter. Not only King James, but the consensus of early seventeenth century scholars, did not believe there was a difference.

By using the well-known word "witch", with its known connotations of someone pledged to serve the devil, rather than simply one who uses witchcraft or dabbles in the dark arts, the translators were arguably influenced by their beliefs, and the goal of using common words, to put into the KJV a nuance which may have been missing in the original.

That the King might simply have commanded this and the translators meekly submitted isn't how power worked in the seventeenth century.

King James VI of Scotland (who later became King James I of England) tried to prove that witches existed and that the Bible said they must be killed. James developed an obsession with witchcraft from an early age, blaming witches for the death of his mother, Mary Queen of Scots. In 1597 he published a book that he had written on the subject of witchcraft, his Daemonologie. After the union of the Scottish and English crowns in 1653, James’ obsession with witches spread into England. As a result, many women were put on trial, tortured and executed. More information here: Daemonologie.

He used Exodus 22:18 as justification for his witch-hunts and executions: “Thou shalt not suffer a witch to live.” (KJV)

The NIV reads: “Do not allow a sorceress to live”.

A female sorcerer is a witch, a female practiser of magic, according to various dictionaries. The male version would be a wizard.

As for tampering with the book of Deuteronomy 18:10-11, I doubt there is any evidence to support the claim that King James wanted “to include words against witchcraft.” Below is the wording from the King James Version, followed by the New International Version translation:

There shall not be found among you any one that maketh his son or his daughter to pass through the fire, or that useth divination, or an observer of times, or an enchanter, or a witch, or a charmer, or a consulter with familiar spirits, or a wizard, or a necromancer. (KJV)

Let no-one be found among you who sacrifices his son or daughter in the fire, who practises divination or sorcery, interprets omens, engages in witchcraft, or casts spells, or who is a medium or spiritist or who consults the dead. (NIV)

The KJV says “a witch” while the NIV says “engages in witchcraft”. Someone who engages in witchcraft is a witch.

I have no idea whether St. Andrews University has a letter from King James asking for the Bible to be changed with regard to witchcraft and witches. Unfortunately, because of the Covid-19 pandemic, I doubt any enquiry about that would be dealt with anytime soon. I think the University is in lockdown.

Here is the link to St. Andrews University Library: https://www.st-andrews.ac.uk/library/

The phone number (in the U.K.) is 01334 462331