Multiboot USB Pen

"It’s possible to get multiboot starting with grml 1.1, grml64 0.2 and grml-medium[64]. This might be useful if you need a 32bit together with a 64bit version on just one medium like a USB pen.

First of all take the 32bit version and install it to your USB pen using grml2usb. Then proceed as follows:"

http://wiki.grml.org/doku.php?id=tips#multiboot_usb_pen