DCS 240+ Set OpSw 36
On a DCS240+, setting an OpSw is actually pretty straightforward. The only tricky part is that OpSw 36, 37, 39, and 40 have a special "execute on restart" procedure.
To execute OpSw 36 (clear slots and consists)
Save a screen shot of the JMRI Slot Monitor.
Move the DCS240+ MODE switch to OP.
Disconnect the layout LocoNet from the DCS240+ (Digitrax recommends programming the command station with only a throttle attached). 
Plug a throttle (DT402, DT500, DT602, etc.) directly into the DCS240+.
Press SWCH (or SWITCH) on the throttle.
Enter 36.
Set it to Closed (C).
- On a DT402/DT500, that's usually the C/- key.
You should get a confirmation beep. 
Now the special part. Move the DCS240+ MODE switch to SLEEP.
Move it back to RUN.
The DCS240+ executes the clear operation during this transition and automatically resets OpSw 36 back to its normal state. 
In the JMRI Slot Monitor confirm that the slots are cleared.