Am I right in presuming you have a legit version of the game (not burned) however can't go on Xbox Live for some reason?
What you linked to for changing the media ID should work if you have a Jtag / RGH hacked Xbox 360 as the title updates for most games are pretty much the same, discs from different regions have different media ID's so require the title update to have that media ID. For a non modified Xbox 360 you can't edit the title updates, as it breaks the signature, essentially meaning meaning the Xbox 360 will see it as corrupt.