One other option might be to try the DBD::Sybase module for DBI. The O'Reilly DBI book says that it provides some support to MS-SQL server.
However it needs a Sybase client library. If you use Sybase's own you may need a SQL server patch so that Sybase clients can see your database.
Otherwise there is apparently a FreeTDS library which is open source for connecting. However this is an Alpha version so I don't know how good it is. Apparently it works OK with DBD::Sybase apart from no ?-style placeholder support.
Hope this helps.