[BILLING] 
host = 123.213.13.2
port = 1433
database = BILLING
user = USER
password = PASSWORD

##</code><code>##

BEGIN{  $ENV{SYBASE}='/opt/sybase....handwaving here...';
}
use DBI;
my $dbh=DBI->connect('DBI:Sybase:server=BILLING') or die $DBI->errstr;