Need help in implementing kinematics of 5 axis XYZAB configuration

I have modified my hobby grade machine to implement 5 axis. According to my requirements I have decided to go for A Rotary axis and rotary head in B. That will give me 4 axis maching which I will planning to use mostly with max stock length and if my peice require 5 axis toolpath, then I can switch to that without changing table.
I have all this implemented in grbl and tested it. Now I want to venture into LinuxCNC world. Since GRBL dont support RTCP. I have searched net and LinuxCNC documents but didn't found info about XYZAB configuration. Didn't even seen youtube videos about this configuration. Here is link to my machine video, it will help in understanding what type of configuration I am using.
www.reddit.com/r/hobbycnc/s/RgIzLvVqyw

Any help in this regard will be highly appreciated.

Thanks for reply and help. I may need some more help. I will try it. Report it back.