It has to be done using diagnostics equipment such as tech2, op-com etc.
The dealer probably wont do it, or will charge you a fortune, as you did not buy the key from them and it might not work properly.
An independent might have a go at it.
You will need the security codes off the "car pass" card, and possibly a new immobiliser chip.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix car alarm systems.