Oh, thats what you mean by auto-indenting. I was expecting it to act like lisp mode where it indents when I press enter (which would be nice to have if someone could manage it).
My problem so far is that when I try to load arc, because the current working directory is not the arc directory, even if it loads as.scm correctly, it can't load ac.scm or any *.arc files. I could set it up to load something like "mzscheme -mf C:\...\arc\as.scm" but I don't know how to make mzscheme look for other arc files in that directory as well.
The standard Emacs indentation behavior is to indent on TAB rather than newline. This is also the default for Lisp-mode, as far as I know. You can rebind this by setting RET to comment-indent-new-line, though.
You need to add some argument to mzscheme to get it to cd into the arc directory. Check the args passed in arc.sh.
Ok, thanks. I hacked a batch file and put it in my PATH so I can start arc from emacs. (Setting arc-program-name failed because run-arc wouldn't respect the quotes around the executable name.)