Here's what I did - and the link with pics: https://www.rs25.com/threads/1998-2-2l-questions.185798/page-2#post-2968169
Installed on '96 Impreza LX w/an AT trans.
Get the following parts:
1. Cruise control module - must match your trans -AT or MT (they are labeled on the module) - the PLUG/connector IS ALREADY THERE and is taped up under the dash just above your left foot. I mounted it to a spot under the dash w/zip ties.
2. Dash CRUISE switch - the PLUG/connector IS ALREADY THERE - just remove the 4 screws on the console piece around the gauges, pop-off the 'blank', plug in the wiring connector and insert the new switch.
3. Brake switch - the cruise brake switch is PLUG/connector IS ALREADY THERE taped just above the brake pedal- just swap switches - Note the threads/adjustment of the existing switch to match the new one...or your brake lights may not work or cruise may not easily disengage.
4. Actuator/Vacuum hose/T-connector/Brackets - under hood connects to throttle cable. PLUG/connector IS ALREADY THERE taped to the harness near the passenger side strut tower. It mounts in the stock location- the Forester brackets worked on my Impreza, too. Use the T-connector to splice into your vac lines on the intake manifold.
5. Steering wheel switch/lever (there is no need to remove the steering wheel!) - 2 star screws to remove to get the airbag off (read up on here about what to do to not set it off - I just removed the Neg battery cable, pumped the brakes a few times), remove the right side of the spring loaded horn actuator, pop-out the blank for the switch to pass thru on the steering wheel, swap the wiring for the switch - uses the same connectors - no splicing necessary, put it back together....
I got all my parts from a '98 Forester and they worked EXCEPT for 2 issues:
1. The cable from the actuator was too short, but it'll still work.
2. The steering wheel switch doesn't work for the Resume or Cancel features, but everything else works. I may try swapping in an 'age-appropriate' Impreza module to see if that fixes it.