Hello J,
All these user-exits will trigger during IW31, the moment you enter a component detail and hit Enter. The pre-requisite is all these user-exits should be listed in a project created through tcode CMOD. Means you create a project (say CNEX) and in that in Enhancements assignment section you need to list these user-exits as shown below. Then these exits will trigger.
Also
One more user-exit which will be of use to you is PPCO0023. Though it is equivalent to exit CNEX0026, I believe this can perform all the three purposes of above CNEX exits, if suitably coded. The pre-requisite rule applies to every user-exit.
Hope this resolves your issue.
Good luck
KJogeswaraRao