teddyjr

I just completed this and let me tell you - it's a mammoth amount of work. To add to mewantkouki's post above you'll also need to change out: both door key lock cylinder assemblies and the trunk lock cylinder (which have magnetic sensors and wiring), both door lock actuators (which are 4-prong harness plugs rather than 2-prong to add sensors), and the two theft relays in the engine bay (attached to the main fuse box with their own cover).
That's the easy part. The hard part is the wiring to support the system. The following harness have several additional circuits which either need to be added or the whole harness swapped: The Engine Bay harness, Main harness (under dash), both Door harnesses, the Body harness (runs down the left side rocker front-to-back), and the Tail harness.
A word to the wise: There's a switch inside the steering column that senses the key has been inserted. This is how you get the Smart Entrance Control Unit to enter program mode. These are usually worn, so make sure yours works by checking it with a volt meter at the SECU.