Feel free to rename ac-scheme to $ or % if you think you'll use it often enough.
If you start using this you'll start finding the need for some of the other functions in that link, which transform data back and forth to the way racket or arc likes it. Come back and ask us more questions when you run into errors like this:
I would just like to point out that Arc/Nu is fully compatible with Arc 3.1, and it doesn't need conversions between Racket and Arc, so it's the easiest way to deal with Racket in Arc programs.