Hi Martin--
Basically, the answer is the same. Your function won't be available until you load it, and it won't load automatically unless it's in one of the startup script locations (custom/init, custom/editinit, custom/doctypes/*).
If you want to load it manually for testing purposes, use the "source" command, e.g. if your function is defined in custom/scripts/myCB.acl,
source myCB.acl
If your script file is in custom/scripts, then you won't have to add the full path, you should just be able to use the base filename with the source command.
Another potential gotcha: if you have defined a package for your script file, you will need to include the package qualifier in your doc_add_callback() call. For example, if you have this at the top of your script file:
package myCallbacks;
then your doc_add_callback() call would need to look like this:
doc_add_callback(0, "tbl_insert_after", "myCallbacks::myCB");
--Clay