Just need to edit the grub.cfg file and add the
option in the boot option line of your particular DSL menu entry.
EDIT: Reread the question and I assume you want to boot from HDD instead of RAM. Find /boot/grub/grub.cfg and REMOVE the --toram option. Use something like nano or vim to open grub.cfg and find the line similar to:
Code:
menuentry 'Damn Small Linux 4.* ' {
You should find the --toram parameter a few lines beneath.