How do I add a new language? The aftermarket ROM I use seems to have the language list parred down to just a couple selections, probably to save space.

I would like to add a language back into the system. I can already set the locale using programs such as MoreLocale 2 so that applications with my language support start with the right locale code, however that doesn't add missing system languages. Having the system in another language would be nice, but the main thing is getting the dictionary files for the keyboard auto-complete. How does one go about adding the language support files for an input language to a system or ROM?

I can access other ROM's or the AOSP project to rip things out, but I don't know where to start. What files do I need and what modifications need to be made? Is there an easy way to do this with say a language-pack or is it hackery all the way?

My ROM is fully rooted and I have adb access if necessary. It's Android 2.3.7 (Unofficial CM 7.1 port for Dream/Sapphire) and I'm using the stock Android keyboard. The language I want is Turkish, although unless somebody has a download to point me to it's mostly the process I'm looking for here.
Adding full language support for a device is done at rom level, the languages that the default keyboard will support are added before compilation and the android keyboard will only give you the option to download dictionaries for the languages it supports.
A good workaround is to download a keyboard app (such as GOKeyboard) that supports adding languages unto it.

Locale changing apps are nice but they may not be as thorough in their translation as a rom that was made or specially translated to a specific/your desired language. If your language is Bi-Di (Bidirectional, such as hebrew or arab) and the rom doesn't support it, it may introduce bugs as well!

The best solution will be to flash a new rom that holds your desired language, either a stock rom made for your area by your device manufacturer or a custom rom, Cyanogen is good because it probably supports every language that complies to the unicode standard (including turkish).