In this kind of emergency, I don't think the format of the radio call is important. What IS important is to tell the tower (Ground Control?) WHO you are, WHERE you are and the NATURE of the emergency. ATC's ground controllers are not complete idiots. If the calling party (Monitoring mechanic on board, a ground-based supervisor or whomever has the presence to give only the LOCATION and NATURE of the problem, ATC's Ground will roll the equipment as requested without a second thought. If questions need to be asked, it will happen after the response is completed. Fire and Rescue folks would always like to know more, but, if they know where they are going, they will NEVER hold their run while waiting for more details. Even if the radio procedure is imperfect, F&R will respond. If additional training is necessary,,,,,, we'll talk about it - after the event. I almost don't believe this question... Fires during non-pilot taxi event are possible, so that's #1. The "Where are you?" and "What is your problem must be stated. Anything else can wait for the in-house or official inquiry. PERIOD. The more one can tell them, the better, but never push your luck. Geez!