Hi Girish,
It is possible to give a search help while you add a field using AET itself within the scree where you give the details of field.
If you want to code it you can also code in get_v
Sample code will look like
CREATE OBJECT rv_valuehelp_descriptor TYPE cl_bsp_wd_valuehelp_f4descr
EXPORTING
iv_help_id = 'your value help name from ddic'
iv_help_id_kind = if_bsp_wd_valuehelp_f4descr=>help_id_kind_name
iv_input_mapping = lt_inmap
iv_output_mapping = lt_outmap.
Here lt_inmap and lt_outmap are the internal tables mapping your importing and exporting attributes of the F4 search help to Attributes within the context node.
Regards
Vinod