-To change your Chocobo, first delete 'tcc_gfx.bmp' inside the 'TCC\GFX\' folder. 

-Now go back to the 'ChocoboDen' folder and rename whichever Chocobo you want to 'tcc_gfx' 

-Copy it to the 'TCC\GFX\' folder, the folder where you deleted the original tcc_gfx.bmp.

-Finished