Maybe try contacting them ? This isn't the right forum to ask about slush pool. They have a support team that is 24/7 available.
I asked people on IRC and some asked me what XT was?! im like.. WTF!!! where have you been? get off of IRC FFS.
Slush pool does support XT. Considering your views you should probably find another pool.
Since tomorrow you'll be able to vote for or vote against this proposal on Slush Pool directly with your miners. Stay tuned!
um.. i don't see a way to change anything regarding nodes in my settings.