I don't know how FXCM does it. I wanted the same thing, realtime FX demo. I found it at Forex.com Real time, 50k demo account for 90 days.
You have to find your way to a page "Open a Demo Account" Signup, get your u/n and p/w. Make a MW connection and use that p/w. You should end up seeing your demo account number in your trade panel. ps... set up a Think or Swim account and check metrics against that, its free and real time and every trader should have a TOS account. imho