I followed a tip from the website below and easily inserted some custom code into the RIAUFMVK program.
http://www.sapdevelopment.co.uk/enhance/eframework/ef_explicit.htm
I left the code as a local transport just to prove I could insert the code.
Explicit enhancement points are basically hooks already coded into the program by SAP at various points of the code. See program RIAUFMVK for examples of these! These are very easy to implement simply go into enhancement mode of SE80 and right click on the enhancement point where you want to add your code and choose u2018Enhancement Implementation->Createu2019 Give it a name, description and assign it to a change request (should not be a Z package) and then simply add the code as normal.
The author says that you shouldn't assign it to a Z package.
What's the reason for that?
Thanks
Ed Baker