USB booting :: RO issues with editing bootloader on usb install

I have been searching the wiki and the forum for an answer to this one. If I missed an existing post please point me in that direction.

I am running DSL 4.2.4 on a thumb drive, no ide drive, no fd, no cdrom, but I have a SATA flash module that I would like to set up as the traditional hard drive. I would like to edit my bootloader to add the cheat code "sata". Here is the problem, the bootloader will not allow me to make changes. I have tried through the shell as root, and I have tried to go through emelFM as superuser. Is there a way to disable the RO, or do I have to reinstall in order to add the cheat code? I would really like to avoid reinstalling...

Thanks in advance.

I have re-installed, so this isn't pressing, but I'm curious about why there is a difference in the ro default settings for the usb install and the hd install. I'm learning.
I think the usb is RO so writing to it won't it wear out.  It is like a frugal install and you might want to have a separate partition on the usb for a backup.  There is way to have a frugal and backup in the same partition but I haven't tried it.  Search the forum on usb AND backup.
Thank you for the note. It helps me understand the reasoning better.

original here.