Guides like https://wprogramming.wordpress.com/2011/07/11/remote-pssessi... don't seem "fairly easy" to me (that's why I said it requires a lot more configuration compared to Enter-PSSession when both parties are in the same domain).
It's essentially, Enable-PSRemoting
And commands 1 to 3 in the following guide after Enable-PSRemoting. Try to ignore the waffle. You probably do want to to disable HTTP though.
http://www.sirchristian.net/blog/2013/03/11/using-powershell...
Trying to get SSH to work with certs can involve just as much or more stuff than that.
Maybe i'll write a super simple guide, just listing the bare commands, since the documentation/tutorials for powershell seem non-existent despite being pretty powerful..
[1] Grep for "http" on this page: http://ss64.com/ps/enter-pssession.html