the STM32F429 Discovery has already mounted a parallel display. That's the same connection interface as your new display needs.
In general it will be nessasary to adapt the Build Environment to your new display by adapting the display configuration. For that you’ll find the 'ew_bsp_display.c/.h files' in the ‘TragetSpecififc' folder, which you can find in the STM32F429 Discovery Build Environment. In the Getting Started Article for the STM32F429 Discovery you’ll find a chapter ‘Custom specific hardware’ that describes how to reconfigure the LTDC display controller.
Please also do care about the framebuffer and screen size configuration in ‘Application/Source/ewmain.c’.
Hopefully this will help. If you have further questions, feel free to ask.