Even if blessbox had -99% exp, you'd still level to 110 almost instantly due to how required experience for these "low" levels is set... Changing it isn't really possible without affecting other starting players.
Thanks for the reply Agatio, short and to the point. Again, I don't mind that it's not possible, it was just an idea that would give more variety to the game in a way that wouldn't affect other players. Now that I know it's impossible to execute without affecting the entire system of progression for all players, I can declare this thread closed.