AFAIK, there is little to no documentation for the PMS web API. I would approach your project the same way I would approach any other channel project where there's no documented API. Monitor HTTP traffic as you explore the existing web app. I like the developer tools in Chrome for that.
Thanks for the reply. I saw in one of the latest newsletters that you can scan a small subset of a section. Is there a thread/documentation on the topic?
I'm not aware of any. I suspect any discussion of it would take place in the "General" Development sub-forum. There is a sticky thread there about "undocumented tips and tricks".