First, you need 3.3 V, so using MAX232 is a bad idea. MAX232 has 2 functions; invert the signal and boost the voltage. You do not want a bigger voltage! Run the PIC at 3.3V and you won't have to worry about level shifting.
If you need an inverted signal, you would simply use an inverter, or tell the PIC to send inverted. A quick check of the manual for PBP will tell you how to get SEROUT to produce TTL or inverted TTL.