Modify .soclib/global.conf as the following:

{{{
config.systemcass = Config(
       base = config.systemc,
       dir = "/path/to/systemcass/",
       libs = ["-Wl,-rpath,%(libdir)s", "-L%(libdir)s", "-lsystemc", "-ldl"],
       )

config.use_systemcass = Config(
       base = config.default,
       systemc = config.systemcass,
       repos = config.default.repos + "/systemcass",
       )
}}}