Yes!
What I write was also in the boardgame so I dont think I am giving out beta info
The diplomatic "sub-game" is quite nice.
You can delay British involvement. I cant honestly say you can prevent it, because the Entente player will want it. Having the UK join you is more important than any other diplomatic goal as Entente. Heck, you can survive Italy fighting you, but you NEED the British to blockade Germany. The blockade, altough only of minor effect at start, will grow into some serious strain as years go by, and will play a crucial role in bringing Germany down.
Italy: this is quite the diplomacy-target! Delaying them is very useful as Centrals, but you will also have other targets, so will the Entente, so I would call this the most tricky country diplomacy-wise.
You can make them join you as Centrals. The best way for that is playing the Diplomatic Poker option as Germany: details are in the game, but basically, you wait until Entente declares war on you. This is costly: you lose your pre-turn before August, but Italy will have an immediate check to see if she will honor her defense treaty with Germany. Austria-Hungary can also give up Trentin for a favorable modifier for the roll, but that will plummet their National Will. Still, one might feel its worth it to get rid of a future front...
As for USA, there are lots of factors in her entry, and yes it can be delayed, or hastened. They do give industrial capacity to Entente, the closer to entry, the more, so it is a constant issue throughout most of the game for both powerblocs.