syslinux.cfg

# create usb disk
cp /usr/lib/syslinux/vesamenu.c32 /mnt
cp /usr/lib/syslinux/memdisk /mnt

# tinycorelinux
wget ftp://distro.ibiblio.org/pub/linux/distributions/tinycorelinux/2.x/release/tinycore_2.1.iso -P /tmp
mount /tmp/tinycore_2.1.iso /mnt/ -o loop
cp /mnt/boot/bzImage /mnt/boot/tinycore.gz /media/USB_MINI/boot/tinycore/

# netinstall
mount mini.iso /mnt/ -o loop
cp /mnt/initrd.gz /mnt/linux /media/USB_MINI/boot/netinstall/

# syslinux.cfg
default boot/vesamenu.c32
timeout 100
menu title Multi Boot USB

LABEL Localboot
localboot 0x80

LABEL Ubuntu
KERNEL /casper/vmlinuz
APPEND boot=casper initrd=/casper/initrd.gz --

label Tinycore
kernel /boot/tinycore/bzImage
append initrd=/boot/tinycore/tinycore.gz

LABEL Backtrack
KERNEL /boot/backtrack/vmlinuz
APPEND boot=casper initrd=/boot/backtrack/initrd.gz --

label Netinstall
kernel /boot/install/linux
append initrd=/boot/install/initrd.gz vga=normal auto url=http://www.panticz.de/pxe/preseed/preseed.seed locale=en_US console-setup/layoutcode=de netcfg/choose_interface=eth0 debconf/priority=critical --

# Links
http://ubuntuforums.org/archive/index.php/t-703905.html