your RIP should support the Eye-one for the other devices for this to work. We use ours to switch between Creo and Fiery RIPs all the time, just walk over to the other RIP and plug it in, use it to calibrate and then back to the other printer. Never tried it on Onyx (drives our wide format work) but cant imagine it doesn't support using it to calibrate. For profile creation you'll need some additional profiling software which should support the eye-one since it's a pretty standard spectro. Depending on the package you got with the KM it might have come with some software for profile creation...look through the discs that came with the printer.
You can get pretty good color matching if you create the profiles for each printer (check with the software to determine how) then use that as a device link profile on the other RIP. You will definitely need RIPs on all devices though, we have a Canon iPF that doesn't have an external RIP that we just print directly to and it doesn't have the ability to use a device link profile.
