BEGIN {
   $ENV{OMNIHOME}="<dir to omnibus>";
   $ENV{SYBASE}="<dir to omnibus libs  OMNIHOME/platform/solaris2 for example>";
}

my $INTERFACES = "$ENV{OMNIHOME}/etc/intefaces.solaris2";

use DBI;

my $dbh = DBI->connect("dbi:Sybase:server=<servername>","user","pass");

...