the old-school independence exploit is what your referring to. you need a usb stick, PS2 gameshark v1.0-2.0 or codebreaker 9.0-9.2 will only work (not sure about v9.3 but v10 will not work). the indie exploit using gameshark will only work on fat PS2s excluding slims. its pointless to this exploit if you can't get a hold of the precise gameshark or codebreaker version (can't find them on ebay anymore).
if you still want to try to hack your PS2 then google for "turn your 007 nightfire game into a trigger disc" tutorial.
PS1/SCPH-7501 | MM3 modchip
PS2 v9 | 250GB hdd | PS3 component cable | katana 32mb mc
PS3/CECH-2001B | 250GB hdd | 3.65 ofw