how to give custom f4 help for select options for multiple selections.

Hi

I have two select options fields are in selection screen one for proje defination and other one is WBS.

Both having multiple selections and ranges.

i have to give f4 help to WBS based on the multiple selections selected by user in Project defination field.

can you please help me on this.

provide me example if any one is there,

Thanks in advance.

kiran