[Game] How do I change shiny odds in Leaf Green/Fire Red?

[LifelessBalme]

I wanted to play Leaf Green/Fire Red using shinies only, however it would take too long using only the normal odds, so I wanted to change them. I've looked already at other threads, however the hex codes in other threads exceed how far my hex codes go in the rom I downloaded. For example, one guy said I could change the shiny odds at byte 0x08044120, my hex code only goes to 0x01000000. Please help.