I see this topic is a few months old with no activity. I thought I'd try to stir up a response here because this is actually a common problem with a lot of lightweight distributions. I have seen the question in countless forums regarding a way to install the OS from a USB device, and in most of the forums it seems to go unanswered and the frustrated would be user just sticks with the preinstalled windows OS or switches to a different distribution that provides ready made images to install from flash drives and floppies. (such as DSL)
There are many brands and models of older laptops out there with no CD drives and only USB ports. The BIOS in many of these older computers will not recognize or boot a USB CD drive. Most of these older models will boot a USB floppy, but not all. There is generally a way to boot a floppy and have it then boot a USB flash drive or hard drive. This is the method the wildly popular DSL distribution offers to install the OS on old laptops with no optical drive. However most distributions, including this one, offer no similar options or images for floppy boot loaders and the ability to install *FROM* a USB drive.
Now, do not mistake what we are asking as how to install *TO* a USB drive from the CD, That is well documented. What we need is a way to install the OS to the laptop's hard drive *FROM* a USB drive of some kind, either with a bootable USB flash drive image or with the help of a boot floppy to load from the USB device.
If anyone has information as to how this can be accomplished with CunchBang please share it so we can bring CrunchBang to this under served market. In the mean time my friends and I that have old lightweight notebooks with no CD drives (Fujistu, Toshiba, and IBM, to name a few) will just continue running DSL until another option comes along.