I'd like a (platform independent) way to list all classes from a package.
A possible way would be get a list of all classes known by Haxe, then filtering through it.
This is one way to store and retrieve the information: https://gist.github.com/back2dos/c9410ed3ed476ecc1007
Beyond that you could use haxe --xml <filename.xml> to get the type information you want, then transform it as needed (use the parser from haxe.rtti to handle the data) and embed the JSON encoded result with -resource theinfo.json (accessed through haxe.Resource).
As a side note: there are chances you'll be better off not having any automation and just add the classes to an array manually. Imagine you have somepackage.ClassA, somepackage.ClassB, ... then you can do
import somepackage.*;
//...
static var CLASSES:Array<Class<Dynamic>> = [ClassA, ClassB, ...];
It gives you more flexibility as whatever you want to do, you can always add 3rd party classes, which may not necessarily be in the same package and you can also choose to not use a class without having to delete it.