FITE_VC_GENERAL_DATA Standard webdynpro component vehicle types are greyed out

In Travel Management(Travel Expense Report) When I am enhancing FITE_VC_GENERAL_DATA Standard webdynpro component ,I want to change dropdown box properties because in dropdown box properties set as READ_ONLY = 'X' so ,I can't changed it.

Running this application via portal dropdownbox UI element Vehicle type is greyed out and it's directly feed from Info type 0017 , I could not changed or select the another vehicle type properties like (Approved car mileage,Bicycle mileage,etc. in the dropdown box) .

Moreover,I can not enhance the method inside the dropdown element,because it's rigid.

Kindly somebody let us know how can I achieved dropdown UI element(Vehicle Type) grayed in and select other properties(Approved car mileage,Bicycle mileage,etc. in the dropdown box) .

I checked the configuration side also and is there any ways to achieve this functionality.

Please Help Us.....

Regards,

Vijay