How to distinguish multiple OS X installations from each other in the bootloader?
Get a 16gb or 32gb usb stick
Partition it with GPT (to have EFI partition on it) if you trying to install os x on non apple hardware = hackintosh use MBR and manually add an EFI partition (EFI specification says it can live with mbr as well)
restore InstallESD.dmg with Disk Utility to a partition for each Installer Image you wish. Just make sure your partitions have at least 5gb space. 


Your partition table on your USB stick could look like this

/dev/diskX1 - EFI

/dev/diskX2 - Osx Lion

/dev/diskX3 - Osx Mountain Lion

/dev/diskX4 - Osx Snow Leopard

/dev/diskX5 - Osx Whatever

install rEFIt on the usb sticks EFI Partiotion to have a boot loader. EFI Partitions are 200mb, named EFI, filesystem type is FAT to check if you got one on your usb stick enter in terminal 
diskutil list and look for EFI in the lists, shoud be '/dev/diskX*s1*' since it's the first partition on GPT based tables 

if trying to use install OS x on non Apple Hardware (==osx86) use Clover V2 instead of Refit. Put your Usb into your computer and boot from it. If you don't see a boot menu on Mac after installing refit - read the readme file and bless the disk from terminal.

Be happy with your uber usb installer