You need 5 things.
1) MPLAB - Download
MPLABX from Microchip.com
2) C18 Lite Compiler - Also from Microchip.com, and on the same page as above.
3)
Kevin Watson's Robot Code, mainly because it works with the above compiler and IDE.
4) IFI Loader (Website might be down?) IFI Loader 4VEX will NOT work.
5) Serial cable for programming.