I replaced the front shocks on a 1996 Infiniti G20. It should be the same process on all P10 and P11 G20 and Nissan Primera models. It was a pretty straightforward repair. The only special tools required are shock compressors. At least here in North America, you can rent those from most chain auto parts stores. It cost me a $55 deposit, which I got back when I returned them. I got the pair of shocks on eBay for something like $65. So far so good.
Please remember not to get under a car resting on the stock tire replacement jack! Jack stands are recommended. If not, at least put a tire under the car and watch where you put body parts. Do not disassembly the shock spring assembly without the spring compressed! And don't try to compress a spring with structural rust or damage that could break.
I didn't replace anything but the shocks themselves, but you can see a blow up diagram here if you need any other parts replaced: www.infinitipa...
This is what I used to make the spacer between the shock assembly and the shock tower: shop.advanceau... I just cut out pieces in the shape of the originals.
Sorry, the sound gets out of sync a bit at the end. Not sure what happened.