I realise that SQL Server is based on Sybase. And that ODBC should be able to take care of this. But, perhaps I've spent more time on perl than on database decisions, I would have thought about DBI::ProxyServer and DBD::Proxy. You may be able to set up a DBI::ProxyServer running on the SQL Server machine which would use DBD::ODBC or DBD::MSSQL. And on Linux, you'd simply connect to the proxy server.

Of course, eventually, you'll want to convince management to move to a more heterogeneous database environment. That would make things immensely easier. :-)