Mike- There is a bleed valve on the self-leveling valve assembly. Here are the applicable pages from the 456 workshop manual. If you do not have one, you can download it from ferraridatabase.com.
It does not say much about bleeding, but probably open the valve until you get fluid only coming out. The system is pressurized by the accumulators and the shock absorbers themselves, so not sure what else needs to be done to ensure all the air is evacuated. The system shares the reservoir with the power steering, but I am unsure there is any other connection with the hydraulic steering system.
Maybe one of the pros can help.
The ECU should be unaffected, since its primary job is to operate the shock actuators, not the self leveling system.
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