This is hard because most live-CD programs expect to have the whole partition to themselves. Putting several bootable programs on the same partition gets very messy.

Solution? Use many different partitions, one per boot-option.

Question: can you do all this without doing extended partitions?

Enhancements

• at boot time, rewrite the partition table so there's only one partition that's "active" at one time
  • this is an advantage to using USB drives... you can't twiddle the partition table on CD's
• after the partition table is twiddled, you could ask the user to just reboot
• oorrrr.... if the target OS is Linux-based, you can directly boot it without first rebooting, by using kexec