1. first install CLEO3
How to do, look at
http://zazmahall.de/ZAZGTASANATORIUM/CLEO3BASIC.htm#CLEO3BASIC_eng

2.
copy Carspawn.cs into GTASA\CLEO - folder


press key 2 to sitch on the carspwner
press forward/backward to switch from model to model
press Enter or Look Behind to confirm and exit