Andrew-
As Hersh pointed out, SB100 was passed to allow kit car builders the option of registering their hand built cars by the year of the car (as stated on the MSO), or by the year of the engine (the date code cast in the block). SB100 limits the number of hand built cars to 500 per year. This being the first year, there are still ~250 available certificates.
If you are in CA, it is a breeze now that the local DMV offices know about it. At the beginning of the year, it was a nightmare as the local DMV offices had no clue to the bill.
The process is simple, but time consuming:
Go to the DMV with all your paperwork and receipts
Ask for a SPCN #.
Get SPCN# and make an appointment with the BAR
Give the BAR tech your SPCN# paperwork. He will check the smog readings. It will undoubtedly be classified as a gross polluter by CA standards. He will put a smog exempt certificate on your car.
Make an appointment with the CHP to obtain VIN. Note: car must be painted as the VIN contains all the car's information (color, engine type, etc.). CHP will put VIN tag on car (usually not where you want it).
Go back to DMV with all paperwork and receipts. Pay BIG ASS fee (tags and taxes from receipts). Get registration and go for a ride.
Hope this helps
Bill D
CA DMV