Multibooting is not quite popular amongst normal users. Normally you'd just want to achieve a regular dualboot and you're set.
It serves a purpose only if you're only purposely booting into multiple os's. If you want to achieve, let's just say, a "dualboot"
consisting of a main os of iOS 7, a secondary iOS of 6, and the final iOS as 6, then you can use this guide to do that such thing.

Firstly, if you want to do a triple-boot, quad, or however many you feel like doing, you need to make sure that you change the "rd=disk0s1s(x)"
variable. We normally set this in the iBEC with the boot-arg of "disk0s1s3," but if we are doing a triple-boot, we need to specify the other
iBEC that we don't intend on using disk0s1s3 and actually use disk0s1s5 as our "third" os. So, make sure its boot-arg is set to "rd=disk0s1s3,
disk0s1s5, disk0s1s7, and etc.

After you set the boot-arg to iBEC, we need to not only tell iBEC what filesystem will be loaded, but its exact location within the main os.
We need to set a variable in iBEC to make sure that we load our correct partition which will contain our third filesystem.

So, as usual, make sure you do the same as every other file we patch. After that is completed, we need to search for a string which we need to
change which will tell iBEC which filesystem we need to load. Enter the strings window and search for "failed to mount upgrade partition."
We need to change "a2" to hold the value of 4, so enter hex view and change "32" to "34." That's literally it. That's how you patch to
enable yourself to multiboot. Pretty simple huh? I'd hope so. This is literally the most simplest patch, along the DeviceTree :D