From page 105-105 of The DCS O Gauge Companion 2nd Edition: (I've highlighted what I think you may be missing)
Next, proceed as follows to select the PS2 subway or trolley and create the route:
• Press Start Up on the DCS Remote to place the PS2 subway or trolley into DCS command mode. Then drive it to the first station at the beginning of the route. Ensure that it is facing forward and ready to proceed forward. If it is a subway, ensure that all the subway cars that will normally be attached to the subway are attached
• Note as closely as possible exactly where the front of the engine is located in the station
• Locate the MTC soft key. If it is not present above soft keys 1 through 4, press soft key S5 (à until it is displayed
• Press the soft key MTC to view the programming soft keys
• Locate soft key MLM (Learn Mode). If it is not present above soft keys 1 through 4, press soft key S5, à,until it is displayed
• Press soft key MLM to enter Learn Mode. The engine will announce that it is in Learn Mode
• Pressing soft key LST (List) repeatedly will announce the names of the stations that may be programmed on the route, in the order in which they appear. Note that as many station names as there are stops on the route must be assigned and that they must be assigned in the order in which they are announced
• Press the LST soft key until the desired name for the first station is announced and press soft key SAV (Save) to assign it. The engine will announce that it is saved
• Drive the PS2 subway or trolley to the next stop on the route slowly enough that it can be stopped at a precise location
• Stop the PS2 subway or trolley and note as closely as possible exactly where the beginning of the engine is located in the station
• As before, press soft key LST until the desired name for this station is announced and press soft key
SAV to save it. The engine will announce that it is saved
• Repeat driving the engine to the remaining stops on the route until it arrives at the last stop and the station name has been assigned using soft key SAV.
If the route is an out-and back route, complete programming the route by pressing the SAV soft key one more time to save the route. The engine will announce that the save is complete. Instead of pressing the SAV soft key twice for the last station, soft key SOB (Save-Out-and-Back) may be pressed once.
If the route is a looped route, complete programming the route as follows:
• Continue to drive the PS2 subway or trolley forward until it returns to the original, starting station
• Stop the engine as close as possible to the place where it was when you began programming the route
• Press soft key LST (List) until the name you originally selected for this station is announced
• Press soft key SAV to assign the station name. The engine will announce that the save is complete. Instead of pressing the SAV soft key, soft key SLP (Save Loop) may be pressed once.
This and a whole lot more is all in MTH’s “The DCS O Gauge Companion 2nd Edition", available for purchase as an eBook or a printed book at MTH's web store!