Hi there. I do use iRule and love it - mostly! However, my integration of it with MC is pretty minimal. I have a few commands (up, down, left, right, enter, play/pause, stop etc.) on some of my pages. However, these are simply buttons that I have programmed to use the MCWS commands with the IP address of the MC instance I want to control. This is sufficient to navigate Theater View if needed, but to be honest the most use of these comes from the OSD. I still use a Logitech K830 keyboard to navigate and find my media, for the most part. I occasionally use JRemote, but that is mostly for mobile listening.
Having said that, iRule can be used to launch external apps on the tablet, so JRemote can be that app. However, once you do this, you are no longer in the iRule app for controlling anything else. Look up JRemote or Gizmo in the huge iRule threads in AVSForum - I never got around to integrating it myself, and in fact I don't see the need to do so any more. Another possible solution to integrating MC is to build in a mouse trackpad into iRule and then use that to control MC. Details on that are also in AVSforum, but I don't know how to do it off-hand.
Oh, I almost forgot: Webpages can be rendered within iRule, so it is possible to make that page WebGizmo. Again, the details are in the AVS thread, but I have found that the iRule support pages are a good forum to get info too.