Removing and replacing the complete throttle body assembly on a SpineFrame Guzzi is an "event."
Replacing the rubber boots? Not so much. Fussy? Yes.
Instead of taking the airbox out (!), release the clamps of the rearward rubber intakes from the back of the throttle bodies and push those rubber tubes out of the way into the airbox.
Yes, the actual intake rubbers are tight fitting, very short, and stiff. Warm your new ones with a heat gun. Nothing extreme, just pliable. I like Shin-Estu grease, but the best temporary (evaporates away) rubber assembly lube I have found it this P-80 Emulsion from "ipcol":