To use Scheme from a shell, you need to add /cse/courses/misc_lang/axp/mit-scheme-7.3/bin to your path (in your .cshrc file). If you don't already have a path, then the line to add is set path = ($path /cse/courses/misc_lang/axp/mit-scheme-7.3/bin). Now you can type scheme at the shell to get the MIT Scheme interpreter.
To use Scheme from EMACS, you should add the following function to your .emacs file:
(defun mit-scheme () (interactive) (load "/cse/courses/misc_lang/axp/mit-scheme-7.3/lib/emacs/lisp/xscheme.el") (run-scheme "/cse/courses/misc_lang/axp/mit-scheme-7.3/bin/scheme"))
Now you can start MIT Scheme by typing Meta-x mit-scheme in EMACS.