Hi,
Here is the starter pack:-))for developing migration scripts
1.Identify the right API for your localisation, for GB, it is HR_EMPLOYEE_API.CREATE_GB_EMPLOYEE
2.Ensure, you identify and pass all the mandatory parameters for the procedure, both IN and OUT and also pass the IN/OUT parameter,epecially object version number, if its create procedure just pass a local variable of type number, in this mode this variable would act as OUT parameter i.e hold the return value from the procedure. if its update procedure, it would act as IN/OUT parameter and you have to pass current OVN of the record.(Hope you understand how OVN works, if not have a read about it, its fundamental to HR and its knowledge is a must).
3.Finally you have to explicitly mention COMMIT in your PL/SQL program or pl/sql wrapper.
One question for you, why you want to move employees from one business group to other, just curious about the business case.
Hope this helps.
Cheers
Sudhir