To copy the schemas into a local directory, do the following.
cvs -d :pserver:anonymous@cvs.freehep.org:/cvs/lcd lcdd cp lcdd/schemas/*/*/*.xsd /mySchemaDir
Then set the GDML_SCHEMA_DIR environment variable to point to this local directory.
GDML_SCHEMA_DIR=/mySchemaDir
Also, SLIC will also automatically search in the current directory for schemas.
The entity resolver in GDML should find the schemas if the structure has been flattened, as in the above configuration. GDML should also be able to find the schemas if the path component of the URL is preserved, i.e. /mySchemaDir/schemas/lcdd/1.0/lcdd.xsd.