There's more to it then I am going to write here. But you need to meet all current ADRs unless you can get a exception.
An outline of the ADRs can be found here:
http://www.dotrs.gov.au/transreg/str_adrindx.htm
You need to pay money to get the full and detailed version. You can get exeptions for AirBags etc as it is an ICV.
The biggest hurdle is emmisions. You will need a current model engine to meet these complete with Cat, PCVs, CarbonCanister etc etc.
Then you just have to sell all you body organs to pay for the engineering aprovals, inspections etc etc and you have yourself a 2005 model buggy.
This is not to be taken lightly. This is extremely expensive. The Cobra guys spend over $60000 to get their cobras on the road, and that is with them doing most of the work themselves. I suspect a Short Wheel base buggy set up to meet current ADRs would cost you $35K+
My recomendation to you chris would be to buy a already going buggy. Learn to drive it, learn what you want, learn from you mistakes. then about 5 years latter start building your dream buggy.
I bought my first buggy 7 years ago. I have spent the last 1 1/2 years and a stupid amount of money building up a new and improved buggy with everything I've learnt and to do everything I want. I still have my original buggy to drive when I want.
[Edited on 13/5/2005 by MikeM]