how to implement custom payment method (APN)

Hi,

I need API which should be used to implement custom payment methods like Perfect Money and BitCoin (BitPay is not acceptable for some reasons).

Also, where is general documentation about system? How can I identify that purchase was made - APN call?

Thanks in advance

Here how to add new payment method: http://www.amember.com/docs/API/Paysystem

However, what if I prefer to have 'popup' payment form with just email and pass?