PIC18 and external flash memory controller code

Hello, I'm using a PIC18F26K22 i need to manage (write/read, edit) data stored in flash memory (AT25SF081) , but i have only 1K ram so is very hard for me manage the external flash , i have 2 sectors availables (64KB each one) and only use 1 of they, so I want some kind of code to manage for me to write/edit/delete to the sector #1 and use sector #2 as dump, you can use a double buffer of 256B So in a short way, i need something like uint8 flash_read_byte (uint24 address); flash_write_byte (uint24 address, uint8 byte ); the code must be written in MPLAB C18 3.47 , the code must be donde in 4 HOURS OR LESS