N00b question, how to swap discs?

[HeXiDeciMaL]

I downloaded Colin McRae3 off the net, and I can play CD1 fine, but how/when do I swap discs for the other tracks?

Whenever i eject CD1, the game freezes, and inserting any of the other CDs won't unfreeze it.

I'm not sure what kind of mod chip is installed because it is not my PS2, but I need to hold the reset/power button for a few seconds when turning on the PS2, and load the games through gameshark2 to play CD-R copies.

Please help
Thanks