i just replaced the barrel on my aerox but it was an entire unit with the steering lock built it if yours is the same you will have to drill out the mounting bolts once you have done that its a fairly simple task of removing the old one n putting the new one in its place an connecting the wires you will have to dismantle the entire front end paneling to do it though
if however you have just got a single barrel you need keys to remove it which kind of defies the point of replacing the old one because you have lost the keys also check your old ignition system as there is two types one has 3 wires the other has 5 make sure you have the right one or itll never work
hope this helps a bit
phil
September 2010