Sorry, but adding code to an HTML component is not a part of the Wix Code product (which is what this forum is about).
The basics of an HTML component is to put any HTML code in it. That code can be copied from Facebook, Google, or anywhere else, but you need to know the exact code to put there (which is not related to Wix Code)… We can’t really help with that.
Were you able to find a solution to this? I am trying to avoid going all in with the Chargebee API and this seems like a great solution, but like you indicated it is difficult due to the iframe.