The attached ZIP file contains an AutoLISP file that defines a command called LKL that will generate all of the layers defined in the current Layer Key Style. It should work in ADT 3.3 through ACA 2009, although I have only tested this directly in 2004. (Most of the code deals with assuring the proper ARX file is loaded for the version of ADT/ACA being run - that was copied from another routine that has been tested in all of those versions.)
Note that if a layer already exists in the drawing in which the command is run, the layer will be left "as is" (just like it is when an AEC command or tool references a Layer Key)>
Also note that if Layer Key Overrides are enabled and any are set, the generated layer names will reflect the override settings.