Acexl: It is plug and play fitment, anyway..
1. you need to find HVAC panel from 1991-1993 model with old dashboard, 1994+ HVAC is not wide enough and has different brackets and shape, I am not sure it would fit 1991-1993 models
2. if you get older HVAC, it is only plug and play without need to cut something
3. you need two electromotors for air boxes under your dashboard, plus a set of small plastic "arms" for one of the electromotors, it is all there in a car with logic-type hvac
4. you need wiring with connectors
5. setup is easy then, if you have A/C, then you need to study Wiring diagram manual a little bit, but the system can be wired to A/C button on HVAC panel
I only miss those electromotos, I would write up a conversion topic, but I can't without those motors
PS: UK logic-type HVAC panel perfectly fits US centre console without gaps. If you use EU centre consoe, there will be a gap above HVAC panel (about 3 mm).