Can you help me with this patch please?

[score]

Hey people, waddup?

Recently i downloaded a rom (DBZ: Legacy Of Gokuu) for my son. I then baught one of those flash advance sets. I followed the instructions precicely but when the rom gets going on his gba, it says, 'Game cannot be played on the hardware found.'
I researched on this and discovered that you can patch games to fix this problem. I am yet to find a patch. Can someone give me a quick guide on how to make patches on my own. This will help me greatly

Cheers;
Score