I shudder to ask, but my client might offer no other SQL (or SQL-like) solution. I know Access has some SQL hooks; are they enough for basic ActiveRecord?
I appreciate all the suggestions to use other databases, but trust me: I've tried convincing them. There is an "approved" list, and no SQL databases are on it. Getting something onto the list could take more than a year, and this project will be done in three weeks.