PayPal Website Payments Pro -- recurring / subscription?

[ntm]

I apologize for asking if this has already been covered somewhere, but
I am having no luck finding any information.

Is there a way to have PPal Website Payments Pro configured to do
recurring payments through Activemerchant? Obviously, it is not a
part of the API, but I wondered if there were ways to modify the API
to support recurring / subscription payments.

Thanks in advance!