You can get access to the hard drive partition in /tmp/harddrive/part1 or partx. For the purpose of this setup, I've created 2 partitions using the web interface. One is the minimum 100 Mb, the other is the remaining space. They will be formated in ext2fs, so it allow us to work seemlesly on this partition and on the system.
First you have to go to the "secret" admin page:
From there, if you type the ls command then click on refresh, you see that there are a lot of pages available, but they only set up nvram parameters, as they are probably missing the firewall or ppoe files.
First, copy your stupid ftp conf file from this page:
if you are ready to copy it on you first partition (add subfolders if needed)
cp /tmp/stupid-ftpd.conf /tmp/harddisk/part1/stupid-ftpd.conf
Then you need to edit your stupid-ftp.conf using a good editor that keeps the unix formating (like ultraedit, not notepad if you are working under windows)
As it is on your first hard drive partition, you can fetch the file using ftp or normal network access on the root of your first partition.
Find the line starting with serverroot=/tmp/harddisk/part1 and replace it by serverroot=/
save your file, and go back the the "secret admin" page
and hit refresh
cp /tmp/harddisk/part1/stupid-ftpd.conf /tmp/stupid-ftpd.conf
now you have to kill the old ftp deamon. Probably that a killall would have a lot more options, but my simple method (i'm rusty on linux) is to use ps -aux in the admin page, find the stupid ftp line, get the PID (the first number in the row) then type kill -9 xx where xx is the number
do the whole trick
all this must be typed then followed by the refresh button, not enter.
to finish, type
and hit refresh.
Et voila, you have an access to the whole system if you ftp your wl-hdd
As a side note, it seems the process wont use a conf file located anywere else than on the tmp folder.
Feel free to correct me, as I said I'm rusty on Linux, but I'll go back on track very quickly