Unit-Testing Acceptance-Tests?

I am currently making some Acceptance-Tests that will help drive the design of a program I am about to do. Everything seems fine except I've realized that the Acceptance-Tests are kinda complex, that is, although they are conceptually simple, they require quite a bit of tricky code to run. I'll need to make a couple of "helper" classes for my Acceptance-Tests.

My question is in how to develop them:

Make Unit-Tests of my Acceptance-Tests(this seems odd -- has anyone done anything like it?)
Make Unit-Tests for those help classes. After I have done all the code of those help classes, I can pass and start working on the real Unit-Tests of my System. When using this approach, where would you put the helper classes? In the tests' project or in the real project? They don't necessarily have dependencies on testing/mocking frameworks.
Any other idea?

Solution

If you think of software development like a car production plant, then the act of writing software is like developing a new car. Each component is tested separately because it's new. It's never been done before. (If it has, you can either get people who've done it before or buy it off the shelf.)

Your build system, which builds your software and also which tests it, is like the conveyor belt - the process which churns out car after car after car. Car manufacturers usually consider how they're going to automate production of new components and test their cars as part of creating new ones, and you can bet that they also test the machines which produce those cars.

So, yes, unit-testing your acceptance tests seems perfectly fine to me, especially if it helps you go faster and keep things easier to change.