Hm? In the hangar you should be able to change the name of the ship before you set out on the journey.
If you mean mods, then you have to change the values between <class></class> and <name></name> tags in blueprints.xml. If you wish to use a custom blueprint (other than all the default ones, like SHIP_PLAYER_HARD), then that's not possible to do with player ships (you have to override an existing ship).
(and by the way, for questions that are unrelated to the current thread, you should create a new topic)
I have installed this mod, which is a great one, but I am unable to stop it from loading. I have reinstalled GMM, and validated FTL's file cache, but no matter when I load a mod into the game, the Viper shows up. Does anyone know how to stop this?