How do I make a bootable CD that will automatically install win98 SE, like the Win2000/XP CDs?

First, you'll need a Win98 boot disk. Assuming that you have this already, you must copy the entire contents of the Win98 cd to a temp directory. If you have the boot disk that came with the boxed Windows 98 cd, then you're ready to start your cd writing application. If not, you'll need to edit the last line of the autoexec.bat file to launch setup from the cdrom drive. Depending on what cd writing software you have, it will be a bit different, but you will start a new 'project' and choose to create a bootable cd. Insert your bootdisk when prompted. Add the entire contents of the temp directory where you copied the cd contents earlier. You should be all set then.

Also take a look at these threads. While not directly answering your original question, you can get some pointers here:

http://www.ntcompatible.com/forums/viewtopic.php?p=112199

http://www.ntcompatible.com/forums/viewtopic.php?t=21978