The best idea would probally be to get a seperate fax machine if you find incoming fax messages to be bothersome. The printer can only perform one function at a time and its on a first come first serve basis. If a fax comes in before a print job then the printer will process the fax until it is done.
Another idea would be to retire your physical fax line and setup an online fax service. Online fax will allow you to manage all your outgoing and incoming fax messages from your email. That way you can print whenever you want as opposed to as soon as the message comes in. Use the normal fax forwarding rules in your email to spread the emails around as necessary.
More info with Online Fax: