I don't believe CCleaner has this (correct me if I'm wrong), it would be nice to have ccleaner have the ability to run your own custom made MS-DOS (prompt, cmd) batch files.
I see no need.
It can be launched by a batch file.
I have a batch file that at the end of the day purges junk which CCleaner will not handle,
after which it launches CCleaner and depending on the command will either :-
Close the DOS window shell/process before CCleaner has got into action , or
WAIT for CCleaner to complete and be manually or /AUTO closed,
where upon the batch file can do other things.
This achieves all that would be obtained with a customised CCleaner that could launch my own scripts.
If I wanted a different script at the start of the day to do different things that included CCleaner it will be no problem.
It would NOT be acceptable to have one version of CCleaner configured for the morning,
and another version configured for the evening.