I figured out how to install Ubuntu with Chameleon after a while. It turns out it doesn't matter if it's ext2, 3, or 4, because it can register (appear) as ext2 to the boot loader. When Installing Ubuntu, on the last screen where it gived advanced options, opt to install the boot loader, but instead of installing it to MBR, select your ubuntu partition from the drop-down box. This will register that you have a boot loader for your ubuntu on the partition, and Chameleon can load it.