Ok, back on topic here guy's!
Making hybrids is just another interesting aspect of Gran Turismo. They are very fun to experiment with as I have found.
There are two ways of making hybrids for your GT2 game.
First, there is the Gameshark. Available in most gaming stores for around $30 USD. There are a bunch of codes that will allow you to make hybrids and if you search for "making hybrids without a Sharkport" or "Part code lists" you will find many more codes.
Then there is the Sharkport for NTSC versions and the Xport for the PAL version games. As you live in Austrailia, you will need the Xport.
The Sharkport/Xport let's your computer and your PS2 communicate with eachother. You can download saves and hybrid vehicles with this device. It also sells for about $30 USD.
To supplement the Sharkport, there is a GT3 (when you decide to work on GT3) garage editing program called the "MK Program." This is an extremely versatile program and is available as a free download. Just do a search of "MK's Program" on this site and look for a download link to it.
If you have any further questions regarding this, I would recomend you to a fellow by the name of Heydu. He is extremely knowledgeable in this area and will be more than happy to assist you.
Hope that helps, and good luck.