Dj,
You may want to call or email Chicago PCA prior to the May 9th DE. I don’t think it is as simple as grabbing a helmet and paying. When I attended the Spring Safety and Tech session in March it was mentioned that your car must have passed a tech inspection and the DE tech inspection sheet must be acknowledged and signed by the driver and an inspector prior to the event :
http://www.pca-chicago.org/?getpage=43
Nick