From what I can see the only option is to script around it using ForceCommand.
It shouldn't be too tricky using Match:
Forces the execution of the command specified by ForceCommand,
ignoring any command supplied by the client and ~/.ssh/rc if
present. The command is invoked by using the user's login shell
with the -c option. This applies to shell, command, or subsystem
execution. It is most useful inside a Match block.
The above are from the man pages. I found more here: SSHD Gatekeeper Script
The best I can muster is running a separate SSHD instance on another port and then adding -s to one of the redirect examples to catch only the application's IP and redirect it to the other instance configured with the right cipher: http://www.cyberciti.biz/faq/linux-port-redirection-with-iptables/