MotionPlus does not require an update, however, the games might. Best choice is to brickblock them and install the required IOS by other means, maybe even patched. Personally, I have used CIOSCorp IOS hacks for IOS versions above 50, which does not share the risk of a full CIOSCorp installation as long as I stay on 3.2. I also use a modchip, one of them old DMS/D2A/D2B kind.