it is very easy all you need to do is swap it for the old one thats located on the right hand side under where the footplate meets the leg shield. If its new, you use both keys to pair the cdi to the keys but if its second hand you need the key and ignition barrel from the bike the cdi came from.
hope this helps
for more help or advice get in touch and i'll do my best.
ruairidh_15@hotmail.co.uk
R.Macleod, August 2008