How to make localized distribution

First step, download Joomla 2.5 [1].
Unpack.
Add your language folder (in my case mk-MK) in /administrator/language/ the admin part and in /language the site part. Remove install.xml from both your language folders.
In /administrator/manifests/packages/ add your language pkg file (in my case pkg_mk-MK.xml).
Open /installation/sql/mysql/joomla.sql in text editor (I use Notepad+). Remember to use UTF-8 without BOM and in this file (joomla.sql) go to part # Languages.
- You'll see (lines 534 and 535 for Joomla 2.5.0, varies from version):
- (600, 'English (United Kingdom)', 'language', 'en-GB', '', 0, 1, 1, 1, '', '', '', '', 0, '0000-00-00 00:00:00', 0, 0),
- (601, 'English (United Kingdom)', 'language', 'en-GB', '', 1, 1, 1, 1, '', '', '', '', 0, '0000-00-00 00:00:00', 0, 0);

Change the ; at the and of line 535 to , and add next two lines:

Next, in same file joomla.sql find (line 1115 in Joomla 2.5.0, varies from version):
- (1, 'en-GB', 'English (UK)', 'English (UK)', 'en', 'en', '', '', '', 1, 1);
- Again change ; at the and to , and add new line (1116 in this case)
- (2, 'xx-XX', 'Yourlanguage-official (XX)', 'Yourlanguage-innative (XX)', 'xx', 'xx', '', '', '', 1, 1);

(in my case):

- (2, 'mk-MK', 'Macedonian (MK)', 'Македонски (MK)', 'mk', 'mk', '', '', '', 1, 1);
- This also set Your language to be default language choice for both, admin and site, sides of your site.
- If you like to use English as default and your language as second options than use:

(2, 'xx-XX', 'Yourlanguage-official (XX)', 'Yourlanguage-innative (XX)', 'xx', 'xx', '', '', '', 1, 0);

Save it.
If you won't to force whole process of installation to your language, and your language is present in in official installation directory, than open file /installation/localise.xml and in line 3:
- <forceLang></forceLang> add your language tag.
- In my case: <forceLang>mk-MK</forceLang>
Now You have Joomla 2.5.0 distribution localized on your language. Zip it and distribute it to Your community. :)