Installation:

Before installation, install smokey8808's Ferrari 458 Italia:
http://www.gta4-mods.com/vehicles/2010-ferrari-458-italia-v30-f9143 or 
http://www.gtainside.com/en/gta4/cars/36388-2010-ferrari-458-italia-v3-0

1: Open the Ferrari 458 Italia's .wtd file licated in 
C:\Program Files (x86)\Rockstar Games\Grand Theft Auto IV\pc\models\cdimages\vehicles.img with OpenIV 
(you will need to be in "Edit mode").

2: Replace the existing 458_sign_1 with the file named as such.

3: Click on save and remember, before you forget, to buckle your seatbelt and enjoy the ride!!!!!