1. Extract the "NEWDUOCHROME3D" folder to your "models" folder

2. In your main ring racers folder, open models.dat with notepad and add these lines to the bottom: 
KNEESOCKS NEWDUOCHROME3D/KKNEESOCKS.md3 3.0 0.0
STOCKING NEWDUOCHROME3D/KSTOCKING.md3 3.0 0.0