Mahesh
We have similar requirements in the past. What we end up with is to use the GATP Transportion and Shipment Scheduling Condition Technique capability (Scheduling Using the Condition Technique - Global Available-to-Promise (Global ATP) - SAP Library).
Basically this mean we create a custom periodic extraction program to extract Route Info (Lead time related to Pick\Pack\Load\Transport etc) from ERP and then map it to individual condition record in APO. This way, user could keep on maintaining the info in ERP as they are used to, and the GATP scheduling results (because the info is also maintained) will respect it too.