Just do a search with the model number of your radio and the words mods or modifications. It most cases you can find either a youtube video or explicit instructions with good photos detailing the process. As PK indicated, in most cases, you just need to remove a small component or clip a wire. You'll need good glasses or a magnifying glass, and a fine point wire cutter.
Some of the manufacturers are very accommodating, and have published service bulletins which detail the modifications. In fact some manufacturers, i.e., yaesu actually provide an access hole in the radio chassis to allow easy access for removing the necessary component. Gigaparts will do the mods on newly purchased radios, I'm not sure if they'll do it for all radios. Mods.dk is one place that has many, many detailed explanations.
