Laserline alarm - progamming a new fob

Hello, and Seasons Greetings!

I see there are a number of posts about Laserline fobs after a flat battery but that is not my particular problem and i couldn’t see an answer in there.

The arm / disarm button on my laserline alarm / immobiliser became stuck and on disembling revealed the button on the circuitry itself is stuck on, as opposed to the rubber button of the fob case merely becoming wedged in as i have had before.

I have bought a new fob but cannot see how i can program it. I would have thought this should be possible from the old one? I would really struggle to get to the alarm itself as it is buried deep within the dash and an absolute pig to get to. Given i have the old fob (which still works but has a faulty button) and the master two pinned manual thing you can put on the plug type thing next to the gearstick (sorry, not very technical) to arm and disarm also I would have hoped i can do this without toooo much trouble. I may be mistaken though!!

Any help gratefully received…

Thanks, Tom