That is probably the wrong end of the connection.
First, setup public key authentication with the Kindle (see the USBnetworking documentation on that - or that ssh thread tutorial I wrote here).
Then that should be the program= option on the public key line in the **Kindle's authorized_keys** file.
(Duh... **not** in my ssh tutorial here, you'll have to go to the 'web for that.)
I am not sure if dropbear sshd (the default in our USBnetworking package) supports the command= option on the public key line in the authorized_keys file, but;
The USBnetworking package also has the openssh sshd included.
Note: the ssh servers in the USBnetworking package are built to use an authorized_keys file in (USB) 'user storage'
- - - - -
The quick and dirty about remote, per key, program execution:
Without this option on a key line (it is per key) in the remote authorized_keys file, the default (for OpenSSH, sshd) is to run: /bin/sh
With this (program= ...) option on a key line, that is what is executed by the remote end (rather than /bin/sh).
man sshd
is really your friend here:
http://linux.die.net/man/8/sshd