Using the free utility CADstudio CsvLayers you can automatically create (import) an arbitrary list of layers to your DWG drawing by reading in a text file with layer definitions.
You can create the layer list in Excel (CSV - comma-delimited values format), or type it in a text editor. The list can contain either the layer names only, or also their properties - color, linetype, lineweight, plot/noplot, visibility… Possible already existing layers will be redefined with the properties from the CSV file.
You can download the application CsvLayers from www.cadstudio.cz/download
An example of the layer definition file:
;CsvLayers sample file
MyHidden,4,Dashed,1,1,1,25,This will be hidden
Ceske Budejovice,,,,,,,My hometown