I have another method:

Let's say you want to mirror <http://sitename.wikispaces.com>

First, create an account on wikispaces. Let's assume the username is "MyName"
and the password is "MyPass". VERY IMPORTANT: You *MUST* login with the
account!

Next, add a URL *with* the username and password. You should get something
like this: <http://MyName:MyPass@sitename.wikispaces.com/>

Then, in the Rules for the project, add "+session.wikispaces.com/*"

Add another URL *without* the username and password, e.g.,
<http://sitename.wikispaces.com/>

Now go ahead and start the mirroring process :)