How to redirect home page so plugin loads

I have installed a non-wpmu plugin that will allow my visitors the opportunity to preview the available themes before they join. However, I don't see in the documentation where to make it load automatically, which is what I want.

My main URL is http://accountingpractitioner.com

I want to load http://accountingpractitioner.com/?themedemo=iNews

Is there a way to have my home URL (only) redirect to the URL. with the parameters?

Thanks,
Kirk