Dynamic Search help in Enhanced infotype

Hi Friends,

I have a scenario, where i need to enhance a standard infotype using PM01.

so i have to provide two fields : Drop Down& input fieldwith search help.

so for drop down i will display values by maintaining at domain level. but for the input field F4 search help, the values changes based on the value selected on drop down.

so how to achieve this dynamic F4 field values based on the value selected in drop down.

Regards,

Siva B