I'm interested in this topic too, but there are gaps in my knowledge. From what I've seen here, your and my 97 will definitely have the electronic system. This is much easier to fit than the older system.
I think what you need is:
1) The cruise control brain or box.
2) An indicator stalk with the cruise switches.
3) The wiring harness for the pedal switches.
I've been watching Ebay and I see sometimes the whole lot, and sometimes just (1), or (1) & (2). The missing bits would be possible to source via breakers, or Neo Bros, or Ebay.
I think fitting just a matter of plugging bits in.
What I don't know is how many pedal switches there are, and how the auto is different from the manual (it must be to some extent because the manual has a clutch switch). Logic tells me there must already be a brake switch for the stop lights, but does the CC hook into this, or is another switch fitted? Maybe on the auto, there are no pedal switches to add.
Also, I have not yet grasped how on the non-TCS cars the throttle control is achieved. There must be some type of actuator, probably a vacuum one like in the old system. But is it guaranteed to be present on all non-TCS cars?
I believe a retro-fitted system will look exactly like a dealer/factory fitted one.