You can find acid-jazz’s breakdown of the .psu save format here, it’s not fully complete and if you can add to it get in touch 🙂
Also added today its a plugin for Total Commander that allows you to browse Xport/Sharkport v2 saves as if they were folders, download it here
Note: This plugin requires and is packaged with XPSTool as it is essentially a gui for the interface 🙂
I’ll be weeding out old information over the weekend and updating the FAQ accordingly with new information such as:
The Action Replay 2.35 released in Europe and the UK is fully capable of restoring GTA3 and GTA:VC saves, use this disc if you do not have or cannot obtain an Xport v2.23