So sorry, very long time no programming.
I don't know how to use the two functions to have it working. GetMeshModel() is used by GetPickedEntity() but how to use it, i'm very lost.
I tryied this but, of course, it's wrong
if (KeyHit(KEY_E)) {
TPick pick;
pick = CameraPick(&pick,cam,Vec3(GraphicsWidth()/2,GraphicsHeight()/2,3.0),2,0,0);
SendEntityMessage(GetPickedEntity(pick,3.0f,0),"use");
}