Problems with usb installation verions 9.2.1

[Nancy E Davis <nedavis@fastmail.fm>]

Hi Debian Folks!

I am attempting to install the current stable 9.2.1 on an ASUS
E200HA laptop using a USB drive as installation media.

I have tried using the non-free firmware update from this location:

http://cdimage.debian.org/cdimage/unofficial/non-free/cd-including-firmware/

I have tried using the regular installation .iso from this location:

http://mirror.math.princeton.edu/pub/debian-cd/current/amd64/iso-dvd/

Both end in the same problem.  

Problem:  During the disk partitioning portion of the installation
program, 
I am unable to *deslect* the USB device I am installing from.  The
result 
is the system repartitions the USB device I'm installing from. 

I have tried setting all the partitions on the USB drive to "do not
use",
but the partition table re-write appears to destroy access to the
information on the USB drive.

When I escape out to a shell, I am unable to find any handy tools like
cfdisk
in order to partition the system drive.  If I can skip the partition
step, I 
think I could get through this.  What partitioning tools are available
to
me in the shell?

I am getting really good at dd'ing a fresh copy of the installation
software
back to my USB ;-D

Suggestions most welcome.  Please let me know if I can provide any
additional information to assist.

Best regards,

Nancy Davis