[Wlug] ssh-dummy-shell for OpenSSH???

I'm setting up a test environment using OpenSSH built in sFTP server. What I want to-do is build a chroot environment where people can connect to the machine via sFTP but not via SSH. I know with the commercial version of SSH they have ssh-dummy-shell which when you try to connect via SSH just bails on you, but lets sFTP work properly. I've done some digging on the web and I haven't found anything that'll replace this functionality on the OpenSSH side of things. Anybody got any ideas/links of an open source version of ssh-dummy-shell. Thanks, Tim.