Newbe question. Can easily use this as a optional default payment?

I am using a series of themes on my network that have different payment gateways. In order to get my site out there I would like to give some of the services away for a few months via pay with a like.

I would like to be able to add it to my payment plan options using this plugin.

I think I am making this a lot harder than what it is I would like to make sure before tearing down the site.

In short I would like to add the pay with the like option to the attached screen shot.

Thank you in advance,

Clay Drake