(updated node)
I have worked with XML_RDB with mysql and Oracle, but never Sybase. The answer to your problem most likely lies in the documentation for DBD::SyBase:

$dbh = DBI->connect("dbi:Sybase:", $user, $passwd);
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You should be able to create a new object like so:

my $xmlout = new DBIx::XML_RDB('Sybase',$user,$passwd);
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Jeff

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