Here's a lightweight version from fading memory...
(This is specifically written for the type 85 - Coupe GT or 4000 models - but with not much adaptation should work well for the type 89 - 80 or 90 models - as well.)
doing the job (it is highly unpleasant, by the way!)
A lift helps a *lot* but the job can be done without one. You at least need the front tires off the ground.
Turn wheel all the way to the left (I think) to make the rack as short as possible.
Now you must separate the pinion shaft from the steering column lower half. This is tough - as I recall it took me a long time and a lot of efforts with various special big hammers and pullers. At this point you are basically pulling the column up away from the rack.
Wrestle the rack out of the car. This is an exercise in four dimensional geometry and advanced Buddhism, by the way. Try to remember how you twisted, turned and moved it along the way so the new one can be Rubiked back into place.
Time for break one...
This is when I played at flushing fluid a bit. The return line will have dumped all its fluid, I think, so I added some fresh to the reservoir and cranked the engine with coil wire to run the pump, for brief intervals, until the stuff that came squirting out of the pressure line was nice and clean looking. I probably removed the old filter (in the reservoir) prior to this and installed the new one afterwards. Just be sure not to run the pump dry, by keeping the fluid level up in the reservoir.
Break one is over, go back to work.
Remove the old firewall seal and install the new one - it has a plastic frame around the rubber part.
Run the video of rack removal backwards and duplicate all your gymnastic procedures to get the new rack roughly into place against the firewall. Make sure all seems happily located, and replace all the nuts and bolts you undid earlier using new locknuts. Leave the steering column to pinion shaft assembly for later - you'll want to make sure the rack is centered at the same time as the steering wheel I think.
Now, hook up the hydraulic lines, carefully. I think I did another flush phase here, or at least used the pump to fill up the rack till it spewed clean fluid.
Center the rack, basically by returning the wheels to the straight ahead position - can be done gently from the tires, since the wheel isn't hooked up yet. If you can manage it, get the lower steering column back on so the wheel is straight as well all at the same time. If it isn't, you can always pull the wheel and recenter it - which might be easier, come to think of it.
Replace and tighten the column to pinion shaft bolt and new locknut and the two bolts holding the column together, rebending the safety metal piece that jam the nuts from undoing.
I suspect at this point everything is reassembled and "fluid tight." Good time to take break number two, while casually but carefully checking every nut and bolt you've touched to make sure it's been reinstalled and torqued properly. End of break number two...
Fill the PS fluid reservoir to the "full" mark and crank the engine (coil off still) a few times to get fluid through the lines and rack etc. as much as possible. When you're satisfied that the level is holding pretty steady, reconnect the electrics so the engine will run, and wiht it running slowly turn the wheel from lock to lock a few times to finish filling/purging the PS fluid. Keep an eye on the reservoir level while doing this. Pay attention carefully for unpleasant noises or inconvenient leaks.
Clean everything up carefully, recheck all your nuts and bolts, and lower the car onto the ground. Take a short, careful test drive to make sure everything works, the wheel is centered, and then check again for leaks.
Take break number three by putting your tools away. If alcoholic beverages are mandated as part of your car repair tradition, please do not perform any more test drives or mechanical work today.
Finally, experience the nervousness which hopefully transforms to exuberance as you drive the car over the next few days and the wheels don't fall off, it goes where you point it, etc.
If you need any more information, I can't help, my brain is sucked dry...