You cannot instruct for a JAA licence or rating unless you hold that same licence and rating or the equivalent issued in a JAA member state. If you wish to instruct for remuneration you will need a minimum of a JAA CPL and FI rating.
I assume that you hold only a Canadian licence, in which case you will need a JAA Class 1 medical, all of the theoretical knowledge exams and, after undertaking an approved course of training, the CPL Skill Test. The amount of training required will be at the discretion of the Head of Training of the FTO involved. You will then have to complete a further approved course of training and pass the flight and ground tests for the FI rating which will be restricted until you have completed 100 hours of flight instruction and supervised 25 student solo flights whilst yourself under the supervision of a flight instructor approved for the purpose.
Since all this will probably take more than a year to achieve, there's probably not much point.