Hi pstranger,
since 2009.2 a lot has changed in the repo, we have a new toolchain, bash, gcc, and much more. Addlocale 3.0 has been updated to work with these new tools and the updated situation in the repo. The best way to add a localization to a fresh install of 2009.2 is to first completely update your system and only after that run addlocale (I just did this for Russian, which I think is your locale you want to add, and it worked perfectly fine). Addlocale can only work properly if the system is in a stable state which ensures that any needed packages for the new localization can be installed without conflict. If you only partially update the system you will almost certainly run into problems.
To fix your system (Note: on 2009.2 you may have to run addlocale from a root terminal)
- run addlocale and reset to en_US
- fully update your system. Ensure all updates were applied successfully, you have no duplicated or broken packages, etc.
- run addlocale and add Russian
Or,
not recommended but still interesting: even this works if your laptop has 2GB of Ram, I'm surprised myself and of course can not guarantee that this will work in the future

- run the 2009.2 liveCD and login as guest
- do not update but run the old addlocale from the CD directly and choose Russian (you can even add OO in Russian)
- after the logout, choose console login, and login as root
- now that all is in Russian, install the russian PCLinuxOS live session to the harddrive
To your questions:
1) you can always 'go back' by running addlocale and resetting to en_US, just ignore any warnings.
2) the language archives are on ibiblio because this is our main server. I don't want to go through the hassle of testing which mirror may have synced or not, the language archives are relatively small and only need to be accessed once when running addlocale.
hope this info is useful, good luck,
-p.