You must first creat an ODBC connection to the Sybase database. That is probrably the hardest part. After creating the ODBC, just Link tables from the Sybase database to the Access front end. When in the Tables window in Access, right click and select Link Tables. Select ODBC from File Types. You will then need to point to the ODBC connection that you created. This will present you with a list of tables to choose from.
You probably need to install the Sybase drivers on the client. After you do this the driver will be listed in the ODBC driver list. Next it is a matter of selecting the server and database to link to. You may need some help from your DBA in this process. The DBA may need to add server information to your sql.ini file that gives the ODBC connection information about the server. I currently have several Access front ends with Sybase backends and they work wonderfully!