Programming PIC from USB using FT232
RX, TX would be enough to send out programming data and get back acknowledgements from the bootloader. Don't forget ground. Also, if you need to use USB only occasionally consider having it extermally (see ft232 basic breakout from Sparkfun,for example).

Edit: you may also want to connect vccio from ft232 to the vcc of the pic to have the same logic levels on both chips.