ESS implementation on MySAP ERP 2004

hi

we have ERP 2004 ECC 5.0 IDES version the online version of ESS is working fine, now we want to use ESS on portal.

now my queries are

what is the prerequisities for ESS on portal ?

is the java components for ESS are to be deployed on Portal Server?

How can setup the SLD for using WebDynpro Application on Portal?

and provide some guidelines to configuring ESS on the Portal Server

regards,

kaushal