This is the best I got:

#NoEnv  ; Recommended for performance and compatibility with future AutoHotkey releases.
AutoTrim, Off
ListLines, Off
SendMode, Input  ; Recommended for new scripts due to its superior speed and reliability.
SetBatchLines, -1
#KeyHistory 0
SetWorkingDir %A_ScriptDir%  ; Ensures a consistent starting directory.
#Include %A_ScriptDir%\Acc.ahk ; Comment out if you put Acc.ahk in the standard AutoHotkey library directory

noBackgroundXmlTemplate =
(LTrim
<?xml version="1.0"?>
<one:Page xmlns:one="http://schemas.microsoft.com/office/onenote/2013/onenote" ID="2.7.Z.E.R.O">
    <one:PageSettings color="automatic"/>
</one:Page>
)

OnShellMessage(wParam, lParam)
{
    global noBackgroundXmlTemplate
    static GetAncestor := DllCall("GetProcAddress", Ptr, DllCall("GetModuleHandle", Str, "user32", "Ptr"), AStr, "GetAncestor", "Ptr")

    if (wParam == 1)
    {
        WinGetTitle, title, ahk_id %lParam%
        if (InStr(title, "OneNote"))
        {
            onApp := ComObjCreate("OneNote.Application")
            winCount := onApp.Windows.Count
            while (winCount--)
            {
                wnd := onApp.Windows[winCount]
                if (wnd.SideNote == -1) ; VARIANT TRUE
                {
                    if (DllCall(GetAncestor, "Ptr", wnd.WindowHandle, "UInt", 2, "Ptr") == lParam)
                    {
                        onApp.UpdatePageContent(StrReplace(noBackgroundXmlTemplate, "2.7.Z.E.R.O", wnd.CurrentPageId))
                        found := true
                        break
                    }
                }
                ;ObjRelease(wnd) ; I never know the release policy with these IDispatch interfaces
            }
            ObjRelease(onApp)
            if (found)
            {
                try 
                    sosa := Acc_ObjectFromWindow(lParam)
                catch
                    sosa := 0

                if (sosa) {
                    for _, x in [[4,3,4,1,4,1,4,1,4,1,4,3,1]]
                    {
                        for _, val in x {
                            oldptr := sosa
                            try {
                                sosa := Acc_Children(sosa)[val]
                            } catch {
                                sosa := 0
                                break
                            } finally {
                                ObjRelease(oldptr)
                            }
                        }
                        if (sosa) {
                            sosa.accDoDefaultAction(0)
                            ObjRelease(sosa), sosa := 0
                            Sleep 100
                            Send, {Down}{Enter}
                        }
                    }
                }
            }
        }
    }
}

ShellUtils_Hook_Start()

ShellUtils_Hook_Start()
{
    global shellHookMsg

    if (shellHookMsg || !IsFunc("OnShellMessage"))
        return

    if (DllCall("RegisterShellHookWindow", "Ptr", A_ScriptHwnd, "UInt")) {
        if (shellHookMsg := DllCall("RegisterWindowMessage", "Str", "SHELLHOOK", "UInt"))
            OnMessage(shellHookMsg, "OnShellMessage")
        else
            DllCall("DeregisterShellHookWindow", "Ptr", A_ScriptHwnd)
    }   
}

ShellUtils_Hook_Stop()
{
    global shellHookMsg
    if (shellHookMsg) {
        OnMessage(shellHookMsg, ""), DllCall("DeregisterShellHookWindow", "Ptr", A_ScriptHwnd)
        shellHookMsg := 0
    }
}

You need Acc.ahk in the same folder. The copy here matches what I downloaded from the original link before the service shut down.