It is not possible to do as you wish.

The Gameshark ORIGINAL is a fundamental part of the boot process. It is a pressed (not burned) CD that has optical properties that are checked by the PS2 in the first part of the boot process. That is why an original is required with current modchips. When that optical check with the laser has occurred, and the PS2 has verified the media, the game type and its apparent validity, the modchip steps in and allows you to swap the backup disk in.

NEO4 and similar, when they come, would have to render information from PROM to the PS2 in such a way that the PS2 thinks it has actually booted from a genuine CD.

Hope that's all clear.