anyone knows which free program can be used to burn the hex file into pic18f2431?

Question

the IC-PROG 1.05 doesn't support this mcu.
or any programmer circuit for this pic? i wanna build one

Answer 1

Find the manufacturer of that chip. They most likely have a programmer for it and/or a piece of software.
If the chip has an in-built USB port, (they do exist now, see Atmel), you could blow the chip directly through your USB port with a front-end program.