There isn't any need for pain.

Here is a very decent overview guide, but it is tailored towards XMR-STAK.  With minimal tweaks to the "StartMining" .bat file, you can get the same automated setup to run with Cast.

https://vegamining.blogspot.co.uk/

And here are some screen shots I took which may or may not help your setup: 

https://imgur.com/a/fuXns

One of my Vega rigs is on a MSI X370 and I am simultaneously mining away with the Ryzen cpu using XMR-STAK-cpu.  The other build is Intel using an older MSI Z97a board that I had.

Both are very stable at this point.

My experience:  install all the Vega cards at once before installing the driver.

Go online to Microsoft and download the Fall Creators Update, which is free.  I was stuck at 3 cards until I did this update.  Working well for me, YMMV.

Do set a very large System page file.