Customization of the leave request ess application

Hi All,

For a customer, I have to change the standard ESS scenario for leave request.
This means that based on a back-end custo table, the webdynpro will have to display different controls based on the leave type.
For example, if leave type is 00 --> Input by time. If leave type is 01 --> Input by custom dropdown, stating half a day, or full day. Calculation of correct hours will be done in back-end.
Can anyone point me in the right direction on how to do this ?

The application is HRESS_A_PTARQ_LEAVREQ_APPL and the configuration HRESS_CC_GUIBBF_LEAVREQ.

Thanks a lot !