Here is something i created a few weeks ago for a poster design that required the Leyton House F1 car, took a while to work out how to do a skin/livery in Assetto Corsa but the results came out sweet. Just unzip and drag your folder to the skins section of the game. Make sure you place the folder in the Lotus 98T section.
F1 Leyton House Lotus 98T Livery 1.0
F1 Leyton House Lotus 98T Livery