Yeah, modding PS2 is not a trivial job. Most people who had any kind of common sense and a decent guide could pick up an iron and mod a PSX in about an hour (most of that time due to being suitably cautious and prepared). PS2 mods are quite different beasts. The main difference is that PSX mods weren't doing anything more than synthesizing a low-speed serial data stream, while PS2 mods do that and perform "on-the-fly" patching of the BIOS, which is on a high-speed paralell ROM bus. This means that the chip takes more power (which means better Vcc/ground routing and thicker wire), and its operation is sensitive to crosstalk and excessively long wires, which means that just putting it in the wrong place can result in an occasional BIOS crash (though this should only occur at startup).