The documentation indicates that you can get the required jars by requesting them from ESRI.
As for version 10.0, ArcSDE is part of the ESRI ArcGIS Server stack, and you may need to request a separate media DVD to ESRI for the ArcSDE Java SDK as it seems it doesn’t come with the standard DVD set but you can get it by just asking for it.
There is also a section on using Direct Connection
ESRI Direct Connect allows clients to directly connect to an SDE GEODB 9.2+ without a need of an SDE server instance, and is recommended for high availability environments, as it removes the ArcSDE gateway server as a single point of failure. ESRI DC needs additional platform dependent binary drivers and a working Oracle Client ENVIRONMENT (if connecting to an ORACLE DB). See Properties of a direct connection to an ArcSDE geodatabase in the ESRI ArcSDE documentation for more information on Direct Connect, and Setting up clients for a direct connection for information about connecting to the different databases supported by ArcSDE.
The GeoTools ArcSDE configuration parameters are the same as in the Configuration Parameters section above, with a couple differences in how to format the parameters:
server: In ESRI Direct Connect Mode a value must be given or the Direct Connect Driver will throw an error, so just put a ‘none’ there - any String will work!
port: In ESRI Direct Connect Mode the port has a String representation: sde:oracle10g, sde:oracle11g:/:test, etc. For further information check ArcSDE connection syntax at the official ArcSDE documentation from ESRI.
instance: In ESRI Direct Connect Mode a value must be given or the Direct Connect Driver will throw an error, so just put a ‘none’ there - any String will work!
user: The username to authenticate with the geo database.
password: The password associated with the above username for authentication with the geo database.
If you have tried these two approaches and still have an issue please ask a further question or clarify this one.