How do I connect to a Sybase database on Windows?

Download and unpack the kit called "ase157_winx64.zip" archive into a temporary directory and run setup.exe. The package installs both 32 bit and 64 bit versions of the Sybase drivers.
e.g. create a Custom installation into C:\Sybase
Make sure you select the 64-bit connector to match your 64-bit Altair SLC installation as we no longer support 32-bit.

When on the modules page select: DB-Library, jConnect 7.0 for JDBC, ASE OLE DB Driver, ASE ODBC Driver and Interactive SQL.
Selected to install a Free Developer Edition of the software:
When the configuration page appeared on the installation window, untick all selections as these are not needed to use the Sybase ASE native drivers and you can always configure them later if you need.
The installation creates the following environment variables:

SYBASE=C:\Sybase
SYBASE_ASE=ASE-15_0
SYBASE_JRE7=C:\Sybase\Shared\JRE-7_0_7_64BIT
SYBASE_JRE7_32=C:\Sybase\Shared\JRE-7_0_7_32BIT
SYBASE_JRE7_64=C:\Sybase\Shared\JRE-7_0_7_64BIT
SYBASE_JRE_RTDS=C:\Sybase\Shared\JRE-7_0_7_64BIT
SYBASE_OCS=OCS-15_0
SYBASE_WS=WS-15_0

and the Windows search 'path' contains:

Path=C:\Sybase\ASE-15_0\jobscheduler\bin;C:\Sybase\ASE-15_0\dll;C:\Sybase\ASE-15_0\bin;C:\Sybase\SCC-3_2\bin;C:\Sybase\DBISQL\bin;C:\Sybase\DataAccess64\ODBC\dll;C:\Sybase\DataAccess\ODBC\dll;C:\Sybase\DataAccess64\OLEDB\dll;C:\Sybase\DataAccess\OLEDB\dll;C:\Sybase\OCS-15_0\lib3p64;C:\Sybase\OCS-15_0\lib3p;C:\Sybase\OCS-15_0\dll;C:\Sybase\OCS-15_0\bin;

Then you should be able to connect to Sybase using a LIBNAME of the form:

libname _dblib sybase user=<user> password=<pwd> server=<servername> database=<databasename>;