[MarketPress eCommerce] Paypal Single Payment Gateway for Marketpress

I user Membership 2 as well and am using the Paypal Single Payments Gateway. I need to be able to use that or similar for Marketpress on this site, but I only see two Paypal options that won't work with just a Single Payment gateway information. How can I use Paypal with my email address and no merchant account with Marketpress? Thanks