Looking a the instructions for Sheevaplug
$this->bbcode_second_pass_quote('', '6').As a root user (using su or sudo), choose one of either mmc (run Arch Linux ARM from an SD card) or nand (run Arch Linux ARM from the internal memory) and run: php runme.sh (mmc|nand)
7.This will extract everything from the USB drive to either your SD card (recommended, at least 1GB in size) or to the internal NAND storage.
After runme.php says it's ready, wait about 5 minutes, then using PuTTY, cu, or screen, connect to your SheevaPlug (using speed 115200). You should be booted into Arch Linux ARM.