Sooooo, you'll have to make a couple of changes.
First is to define the inputfield itself:

/// <summary>
/// Input field object
/// </summary>
private class CuiInputField
{
    public CuiInputFieldComponent InputField { get; } = new CuiInputFieldComponent();
    public CuiRectTransformComponent RectTransform { get; } = new CuiRectTransformComponent();
    public float FadeOut { get; set; }
}

Once you have this, you'll need to extend the `CuiElementContainer` class to make it support the input field:

/// <summary>
/// Custom version of the CuiElementContainer to add InputFields
/// </summary>
private class CustomCuiElementContainer : CuiElementContainer
{
    public string Add(CuiInputField aInputField, string aParent = Cui.ParentHud, string aName = "")
    {
        if (string.IsNullOrEmpty(aName))
            aName = CuiHelper.GetGuid();

        if (aInputField == null) {
            return string.Empty;
        }

        Add(new CuiElement {
            Name = aName,
            Parent = aParent,
            FadeOut = aInputField.FadeOut,
            Components = {
                aInputField.InputField,
                aInputField.RectTransform
            }
        });
        return aName;
    }
}

Then you can add them to the UI (I tend to put them ontop of a panel to give it some shade behind it.
The command it expects is a generic `Command` for `CovalencePlugin` and a `ConsoleCommand` for a rust-specific plugin (Rust-specific should be avoided).

Command example:

private Dictionary<string, string> FExampleInputText= new Dictionary<string, string>(); // Format: <userId, text>

[Command("example.exampleinputtextcb")]
private void ExampleExampleInputTextCallback(IPlayer aPlayer, string aCommand, string[] aArgs)
{
    if (aArgs.Count() <= 0) {
        if (FExampleInputText.ContainsKey(aPlayer.Id))
            FExampleInputText.Remove(aPlayer.Id);

        return;
    }

    if (FExampleInputText.ContainsKey(aPlayer.Id)) {
        FExampleInputText[aPlayer.Id] = aArgs[0];
    } else {
        FExampleInputText.Add(aPlayer.Id, aArgs[0]);
    }
}

var TestNameInput = new CuiElement
{
    Name = "TestNameInput ",
    Parent = ParentClass,
    Components =
    {
        new CuiInputFieldComponent
        {
            Text = string.Empty,
            CharsLimit = 40,
            Color = "1 1 1 1",
            IsPassword = false,
            Command = "example.exampleinputtextcb",
            Font = "robotocondensed-regular.ttf",
            FontSize = 10,
            Align = TextAnchor.MiddleLeft
        },

        new CuiRectTransformComponent
        {
            AnchorMin = anchormin,
            AnchorMax = anchormax
        }
    }
};

container.Add(TestNameInput);​

Then, make sure you add the dictonary at the top.

private Dictionary<string, string> FExampleInputText= new Dictionary<string, string>();​

Lastly, for RustPlugin classes you would use the ConsoleCommand which is shown down below.

[ConsoleCommand("example.exampleinputtextcb")]
private void ExampleExampleInputTextCallback(ConsoleSystem.Arg arg)
{
    BasePlayer player = arg.Player();

    if (arg.Args.Length <= 0)
    {
        if (FExampleInputText.ContainsKey(player.UserIDString))
            FExampleInputText.Remove(player.UserIDString);

        return;
    }

    if (FExampleInputText.ContainsKey(player.UserIDString))
    {
        FExampleInputText[player.UserIDString] = arg.Args[0];
    }
    else
    {
        FExampleInputText.Add(player.UserIDString, arg.Args[0]);
    }
}

Thanks for all the help, hope I can help out those that don't want to switch!

Again, avoid the legacy RustPlugin parent.. ;)

Won't be there in uMod