CentOS install spanning 2 or more CDs

I have a custom CentOS install which used to fit on 1 CD. With recent additions, it takes up more space than can fit on 1 CD. Some of our customers have old systems that aren't DVD compatible so we have to distribute our product on an install CD which now needs to be 2 CDs. What is the easiest way to setup our install to span 2 CDs?? So far, I've discovered the .discinfo file which specifies how many install discs there are. For Example, CentOS 5.5:

1272587247.016243
Final
i386
1,2,3,4,5,6
CentOS/base
/home/buildcentos/CENTOS/5.5/en/i386/CentOS
CentOS/pixmaps

After the i386 line, the number of installation CDs is displayed. In this example, '1,2,3,4,5,6'. How does one decide what RPMs and such to put on other CDs when the install grows past 1 CD??