I was on the Oosterdam recently and there was always someone on hand in the computer area (tenth level, I think) to help you with similar projects. Computer access to the net can be frustratingly slow. Wireless access from the stateroom sometimes works well.
I wouldn't be all that happy having to worry about doing this during a cruise, however. I would prefer to have someone onshore authorized to handle the details -- I would be able to read messages about the deal on the ship, then send emails to the authorized party to handle stuff like printing and signing. Maybe that's just me, though.
In case of problems, there is a nice bar area (and coffee bar) right next to the computers. And a pretty current library.