Creating an infotype and assigning code to it

When I create an infotype (PM01), the screen, module includes, etc. get generated. When I include code in the modules of this infotype the infotype then behaves as I want it to.

The problem I have is that if I (or anyone else for that matter) go to PM01 and regenerate this infotype then the modules are regenerated and my code is lost.

I can get around this by putting my code in the user exit but this is not really the best way of doing this.

Any help greatly appreciated.

Regards,

Jessica.