AbleCommerce Shopping Cart Software

I'm trying to set up my test store to allow payment via a paypal sandbox account. We only use Website Payments Standard. I've added paypal as a payment gateway and know I need to enter the configuration values. But I can't figure out how to set up the appropriate type of business account. When I tried using a preconfigured account, my site started displaying the express paypal checkout option which we don't offer.

Does someone know what you need to set up in the developer sandbox for Website Payments Standard?

Thanks in advance.