How to bypass an Immobiliser on a Speedfighter?

Does anybody know how to bypass the immobiliser on an R reg peugeot speedfighter? you see my mate beign an idiot left his keys in it and sumbody swiped them. hes had it at a garage for 5months and there palying him for a mug so i have resorted to doing it myself for him. he doesnt have any other keys, so i have to get new barrels and locks as well. fitting them shouldnt be a problem its just the immobiliser that im stuck on and what to do with it. Any suggestion would be great. Please email me on jajmoss@hotmail.com cheers