super-imposing models in a java 3d applet

mocdr

I am currently undergoing a project whereby people can view a 3d model of their car, and subsequently add new parts such as alloys or a new spoiler etc. The user would be able to save these configurations but the system would not save the actual model but rather its session details. So the system would not store more models but have the combinations. A table of cars with parts, would store the co-ordinates of the pre-defined locations of how the part should be streamed across and super-imposed onto the car in the applet.
How do I render a scene of a car with these parts in an applet in x3d?