Dale Worley has written a TECO interpreter in elisp. You can find the latest version, v7, here: Lisp:teco.el. Note that there is a bug when it is used with Emacs v22. Since the prompt string in a minibuffer is now returned as a form field, using a non-null ‘teco:prompt’ value causes ‘teco:command’ to fail to read your command string properly. Setting ‘teco:prompt’ to “” works around it.
The following patch should fix the above mentioned prompt problem: http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/app-emacs/teco/files/teco-7-minibuffer-prompt.patch?view=markup I’ve tested it with GNU Emacs 23.3 and 24.0.91. – ulm