The following MRLC datasets are published as map services. These map services are available as Open Geospatial Consortium (OGC) Web Map Serivce (WMS) services. The below links will provide the metadata about the service from the GetCapabilities request.
Using the MRLC OGC Services
The following links provide tutorials on how to add the MRLC WMS layers to the QGIS and ArcMap clients.
Note: Use version 1.0.0 in the import settings when adding the WCS layer in ArcMap. No user name or password is needed.