They changed their hiring process about a half year ago and including sim eval now.
It will be done at Advanced Aviation Simulators(Advanced Aviation Simulators - Denver Pilot Training - Airline Pilot Prep - Recurrent Training, Insurance Approved - IFR Club) in Centennial Airport.
I do recommend to call Lisa Neifert and get as much session scheduled as you can afford ahead of time.
Most probably you will be asked to fly ILS approach started with DME arch to one of GLA airports. So do expect either CO/WY or ND ILS approaches.
Nothing too extreme, they just checking that you are able to fly six pack, have basic knowledge of RMI, able to follow glide slope etc.
Good luck.