Could someone explain how to reference phalcon classes in Zephir?

I found this github post, but wasnt able to figure it out completely:

I found when using this code, and having the phalcon ext directory in /usr/include/php/ext/ (in CentOS anyway) it would attempt to include the files, but fail eventually.

// my .zep file after namespace declaration
#include <ext/phalcon/phalcon.h>
#include <ext/phalcon/forms/form.h>
In file included from /usr/include/php/ext/phalcon/phalcon.h:12,
                 from /mnt/devhttp/zext/ext/zext/forms/form.c:19:
/usr/include/php/ext/phalcon/acl/adapter.h:23:25: error: php_phalcon.h: No such file or directory

Just wondering if this is fully supported yet, and how to do it. I'm not sure which specific files go where or the correct syntax. Is it possible to extend a Phalcon class this way?

EDIT I found this thread on the github issue tracker. Someone posted a fork that lets you extend phalcon classes. It seems to work. I'm just curious why its not officially supported.