I'm not sure if there's a limit to the amount of systems you can multiboot but have you considered use Oracles Virtual Box and run it in as a virtual machine? Virtual box is free and pretty easy to setup.
I have it on vm and live USB, live USB allows me to use my wireless card as VM doesn't. The USB freezes a lot, and I'm a IT security student so I use backtrack a lot and don't want to struggle with a persistent USB after all the reading I have done on that. I have a Linux user issue that shows multiboot but its for like 6 or 8 and I was wondering if there was an easier way for a 3 boot. Thanks tho!
Using a good bootloader should make this easy. I use grub and grub 2 for my multi boot setup. At some point depending on the OSes you will have to learn to code the boot yourself. This said there are programs that will easily set up only 3. You can also have grub 2 chainloading grub4dos so have fun.