Using APM to authenticate ADFS SOAP

We are currently in the process of moving to ADFS 3.0. Part of this project is to use APM instead of ADFS servers in the DMZ. This is working perfectly for all vendors except one. They don't login at a webpage like the rest of our vendors, they have the login built in to their application. From what I understand, they then communicate with our ADFS 2.0 servers via SOAP to authenticate. I'm trying to replicate this on the F5 but I don't know where to start. Has anyone had to do this before and if so, what approach did you use to tackle this?

 

Any help is greatly appreciated.