Hi,
I think I found the solution to my above mentioned problem.
I have tried few configurations in LORD_MAPPING table but never a value help was available for the field(XXX). Apart from above configuration mentioned, coding needs to be done at CRM side for getting the value help for field(XXX).
In ERP_H/HeaderDetail view navigate to the context node in which the custom field (XXX) is available and enhance V_Getter method as shown below.
Also enhance the P_GETTER method, during display mode set the FIELDTYPE property to TEXT and during edit mode set the FIELDTYPE property to PICKLIST.
Now custom field will have value help on CRM Web UI.
SAP NOTE 1637489, can be implemented to improve the performance.
Thanks and Regards,
Ravi.