Another Language Pack in the Windows Phone 8

I need to ADD language pack to Windows Phone 8 for phone model HTC 8X AT&T (PM23300) - USA market. This phone model HTC 8x is also selling in EUROPE with EU language packs already preinstalled in the ROM of the phone. I can't flash the USA phone with EU ROM. Maybe we can extract phone languages (I need GERMAN, Russian, Polish packs) from European version of this ROM of this model HTC 8X and compile it to the PM23300 ROM for AT&T USA ... This is just my advice ... its up to you how you will do it... ALL I need is another language in the settings so I can pick German, Russian, Polish. Maybe you can find online some software that ADD other languages to WINDOWS PHONE 8 ... that will do the job for you ... Thank you