Where is the CRC Checksum stored on a Windows XP Install CD?

I need a customized Windows XP Pro Install CD (please just accept this rather than question it). I’ve made the necessary changes, but now when I try to run it, it gives me a CRC error and won’t install.

Note that this is NOT the fault of the CD, but rather the result of my changes altering the CRC.

I can calculate and correct this value, but I don’t know where it’s stored on the CD. Does anyone know?

Thanks!