By default the metadata import process will walk all of the metadata. Unfortunately sybase appears to report erroneous metadata for some of the system tables - https://issues.jboss.org/browse/TEIID-3064
The simplest properties you typically can set are
importer.schemaPattern - Uses a like predicate pattern to select which schemas should be used
importer.excludeTables - Uses a regex against the full Teiid name to exclude tables from being loaded, so in your case you could want something like DBA.* or *.SYS*