In Messages > Options > General Options, set Make PIN Messages Level 1 to Yes. Then set your Level 1 Messages tone to what you want to sound when you get a PIN message.
__________________ The difference between stupidity and genius is that genius has its limits. When you take things for granted, the things you are granted, get taken. Even a mosquito doesn't get a pat on the back until it starts to work. Too many people miss the silver lining because they're expecting gold. [BES 5.0.3 / GroupWise 2012 HP2]