Happy Halloween!
Just wanted to let you know that DAP now works with 2Checkout.com.
The new file is dap-2co.php and it has been rolled into the existing dap_v4.2.1.zip file, and is available for download in the member's area (if you already are on 4.2.1, you will have to download the zip file again, sorry! 
And the documentation for 2Checkout integration can be found here.
Cheers!
– Veena & Ravi
The DapperGangers
P.S: By the way, we've actually completed integration with WP eStore too!
The code and documentation for that will be available shortly.