With guidance from Floris's reply, I have managed to achieve setting a column from an Automation Script. Below are some methods to hopefully help someone in the future.

Basic Method

SetColumn(engine, 127001, 1234, 1000, 1005, new[] { "1", "2" }, new object[] { "Hello", "World" });

public void SetColumn(Engine engine, int dataMinerId, int elementId, int tablePid, int columnPid, string[] keys, object[] values)
{
if (keys == null || keys.Length == 0)
{
throw new ArgumentException("Cannot be null or empty.", "keys");
}

if (values == null || values.Length == 0)
{
throw new ArgumentException("Cannot be null or empty.", "values");
}

var primaryKeys = keys.Cast<object>().ToArray();
var ids = new object[] { dataMinerId, elementId, tablePid, columnPid };
var tableData = new object[] { primaryKeys, values };

try
{
var message = new SetDataMinerInfoMessage()
{
Var1 = ids,
Var2 = tableData,
What = (int)NotifyType.NT_FILL_ARRAY_WITH_COLUMN_ONLY_UPDATES,
};

engine.SendSLNetSingleResponseMessage(message);
}
catch (DataMinerCOMException e)
{
if (e.ErrorCode == -2147220718 || e.ErrorCode == -2147220916)
{
// 0x80040312, Unknown destination DataMiner specified.
// 0x8004024C, SL_NO_SUCH_ELEMENT, "The element is unknown."
throw new ArgumentNullException(FormattableString.Invariant($"Element with DMA ID '{dataMinerId}' and element ID '{elementId}' was not found."), e);
}
else if (e.ErrorCode == -2147220959)
{
// 0x80040221, SL_INVALID_DATA, "Invalid data".
throw new ArgumentNullException(FormattableString.Invariant($"Invalid data - element: '{dataMinerId}/{elementId}', table ID: '{tablePid}', column ID: '{columnPid}', data: {JsonConvert.SerializeObject(tableData)}"), e);
}
else
{
throw;
}
}
}

IDms Extension Method

var dms = engine.GetDms();
var element = dms.GetElement("Test Protocol");
var table = element.GetTable(1000);
var column = table.GetColumn<string>(1005);
column.SetValues(new[] { "1", "2" }, new object[] { "Hello", "World" });

public static class IDmsExtensions
{
public static void SetValues(this IDmsColumn column, string[] keys, object[] values)
{
if (keys == null || keys.Length == 0)
{
throw new ArgumentException("Cannot be null or empty.", "keys");
}

if (values == null || values.Length == 0)
{
throw new ArgumentException("Cannot be null or empty.", "values");
}

var table = column.Table;
var element = table.Element;

var primaryKeys = keys.Cast<object>().ToArray();
var ids = new object[] { element.AgentId, element.Id, table.Id, column.Id };
var tableData = new object[] { primaryKeys, values };

try
{
var message = new SetDataMinerInfoMessage()
{
Var1 = ids,
Var2 = tableData,
What = (int)NotifyType.NT_FILL_ARRAY_WITH_COLUMN_ONLY_UPDATES,
};

element.Host.Dms.Communication.SendSingleResponseMessage(message);
}
catch (DataMinerCOMException e)
{
if (e.ErrorCode == -2147220718 || e.ErrorCode == -2147220916)
{
// 0x80040312, Unknown destination DataMiner specified.
// 0x8004024C, SL_NO_SUCH_ELEMENT, "The element is unknown."
throw new ElementNotFoundException(element.DmsElementId, e);
}
else if (e.ErrorCode == -2147220959)
{
// 0x80040221, SL_INVALID_DATA, "Invalid data".
var message = FormattableString.Invariant($"Invalid data - element: '{element.DmsElementId.Value}', table ID: '{table.Id}', column ID: '{column.Id}', data: {JsonConvert.SerializeObject(tableData)}");
throw new IncorrectDataException(message);
}
else
{
throw;
}
}
}
}