In order to order a key enabled Chelsea switch, one must do the following:
1. Specify the part number of the Chelsea switch.
2. Add "KEC" to the end of the Chelsea switch's part number.
3. Order the key enable switch.
The end result for a two button chelsea with white plate and buttons beside a key enabled switch that mimics that would be the following:
CH2 BWH PWH KEC
KE PWH